diff --git a/zipline/history/__init__.py b/zipline/history/__init__.py
new file mode 100644
index 00000000..c79b501b
--- /dev/null
+++ b/zipline/history/__init__.py
@@ -0,0 +1,14 @@
+from . history import (
+    HistorySpec,
+    days_index_at_dt,
+    index_at_dt
+)
+
+import history_container
+
+__all__ = [
+    'HistorySpec',
+    'days_index_at_dt',
+    'index_at_dt',
+    'history_container'
+]
diff --git a/zipline/history/history.py b/zipline/history/history.py
new file mode 100644
index 00000000..1e1ce2a7
--- /dev/null
+++ b/zipline/history/history.py
@@ -0,0 +1,120 @@
+from __future__ import division
+
+import numpy as np
+import re
+
+from zipline.finance import trading
+
+
+def parse_freq_str(freq_str):
+    # TODO: Wish we were more aligned with pandas here.
+    num_str, unit_str = re.match('([0-9]+)([A-Za-z]+)', freq_str).groups()
+    return int(num_str), unit_str
+
+
+class Frequency(object):
+    """
+    Represents how the data is sampled, as specified by the algoscript
+    via units like "1d", "1m", etc.
+
+    Currently only one frequency is supported, "1d"
+    "1d" provides data keyed by closing, and the last minute of the current
+    day.
+    """
+
+    def __init__(self, freq_str):
+        # The string the at the algoscript specifies.
+        # Hold onto to use a key for caching.
+        self.freq_str = freq_str
+        # num - The number of units of the frequency.
+        # unit_str - The unit type, e.g. 'd'
+        self.num, self.unit_str = parse_freq_str(freq_str)
+
+
+class HistorySpec(object):
+    """
+    Maps to the parameters of the history() call made by the algoscript
+
+    An object is used here so that get_history calls are not constantly
+    parsing the parameters and provides values for caching and indexing into
+    result frames.
+    """
+
+    @classmethod
+    def spec_key(cls, bar_count, freq_str, field, ffill):
+        """
+        Used as a hash/key value for the HistorySpec.
+        """
+        return "{0}:{1}:{2}:{3}".format(
+            bar_count, freq_str, field, ffill)
+
+    def __init__(self, bar_count, frequency, field, ffill):
+        # Number of bars to look back.
+        self.bar_count = bar_count
+        if isinstance(frequency, basestring):
+            frequency = Frequency(frequency)
+        # The frequency at which the data is sampled.
+        self.frequency = frequency
+        # The field, e.g. 'price', 'volume', etc.
+        self.field = field
+        # Whether or not to forward fill the nan data.
+        self.ffill = ffill
+
+        # How many trading days the spec needs to look back.
+        # Used by index creation to see how large of an overarching window
+        # is needed.
+        self.days_needed = calculate_days_needed(
+            self.bar_count, self.frequency)
+
+        # Calculate the cache key string once.
+        self.key_str = self.spec_key(
+            bar_count, frequency.freq_str, field, ffill)
+
+
+def calculate_days_needed(bar_count, freq):
+    """ Returns number trading days needed.
+    Overshoots so that we more than enough to sample from the current
+    frequency slot plus previous ones.
+    """
+    if freq.unit_str == 'd':
+        return bar_count * freq.num
+
+
+def days_index_at_dt(days_needed, algo_dt):
+    """
+    The timestamps of previous days closes with the size of @days_needed
+    at @algo_dt.
+    """
+    env = trading.environment
+
+    latest_algo_dt = algo_dt
+
+    current_index = env.open_and_closes.index.searchsorted(algo_dt.date())
+
+    previous_days_num = days_needed - 1
+
+    previous_days = env.open_and_closes['market_close'][
+        current_index - previous_days_num:current_index]
+
+    # Using the 'rawer' numpy array values here because of a bottleneck
+    # that appeared when using DatetimeIndex
+    return np.append(previous_days.values, latest_algo_dt)
+
+
+def index_at_dt(history_spec, algo_dt):
+    """
+    The index, including @algo_dt at the given @algo_dt for the count
+    and frequency of the @history_spec.
+    """
+    days_index = days_index_at_dt(history_spec.days_needed, algo_dt)
+
+    frequency = history_spec.frequency
+
+    if frequency.unit_str == 'd':
+
+        index_of_algo_dt = days_index.searchsorted(algo_dt)
+
+        start_index = index_of_algo_dt + 1 - history_spec.bar_count
+        end_index = index_of_algo_dt + 1
+
+        return days_index[start_index:end_index]
diff --git a/zipline/history/history_container.py b/zipline/history/history_container.py
new file mode 100644
index 00000000..eda42279
--- /dev/null
+++ b/zipline/history/history_container.py
@@ -0,0 +1,316 @@
+import numpy as np
+import pandas as pd
+
+from . history import (
+    index_at_dt,
+    days_index_at_dt,
+)
+
+from qexec.sources.history_source import populate_initial_day_panel
+
+from zipline.finance import trading
+from zipline.utils.data import RollingPanel
+
+# The closing price is referred to be multiple names,
+# allow both for price rollover logic etc.
+CLOSING_PRICE_FIELDS = {'price', 'close_price'}
+
+
+def create_initial_day_panel(days_needed, fields, sids, dt):
+    index = days_index_at_dt(days_needed, dt)
+    # Use original index in case of 1 bar.
+    if days_needed != 1:
+        index = index[:-1]
+    window = len(index)
+    rp = RollingPanel(window, fields, sids)
+    for i, day in enumerate(index):
+        rp.index_buf[i] = day
+    rp.pos = window
+    return rp
+
+
+def create_current_day_panel(fields, sids, dt):
+    # Can't use open_and_close since need to create enough space for a full
+    # day, even on a half day.
+    # Can now use mkt open and close, since we don't roll
+    env = trading.environment
+    index = env.market_minutes_for_day(dt)
+    return pd.Panel(items=fields, minor_axis=sids, major_axis=index)
+
+
+def ffill_day_frame(field, day_frame, prior_day_frame):
+    # get values which are nan-at the beginning of the day
+    # and attempt to fill with the last close
+    first_bar = day_frame.ix[0]
+    nan_sids = first_bar[np.isnan(first_bar)]
+    for sid, _ in nan_sids.iterkv():
+        day_frame[sid][0] = prior_day_frame.ix[-1, sid]
+    if field != 'volume':
+        day_frame = day_frame.ffill()
+    return day_frame
+
+
+class HistoryContainer(object):
+    """
+    Container for all history panels and frames used by an algoscript.
+
+    To be used internally by algoproxy, but *not* passed directly to the
+    algorithm.
+    Entry point for the algoscript is the result of `get_history`.
+    """
+
+    def __init__(self, db, history_specs, initial_sids, initial_dt):
+
+        self.db = db
+
+        # All of the history specs found by the algoscript parsing.
+        self.history_specs = history_specs
+
+        # The overaching panel needs to be large enough to contain the
+        # largest history spec
+        self.max_days_needed = max(spec.days_needed for spec
+                                   in history_specs.itervalues())
+
+        # The set of fields specified by all history specs
+        self.fields = set(spec.field for spec in history_specs.itervalues())
+
+        self.prior_day_panel = create_initial_day_panel(
+            self.max_days_needed, self.fields, initial_sids, initial_dt)
+
+        # The panel should contain values dating before the first algodt.
+        # The following call does the 'backfilling' so that `get_history`
+        # will return full values on the first `handle_data` call.
+        # Backfill not needed if only 1 bar
+        # Also, only backfill if a database is available; the main case
+        # where there is no database available is during unit testing.
+        if self.max_days_needed != 1 and self.db:
+            populate_initial_day_panel(self.db,
+                                       self.prior_day_panel)
+
+        # This panel contains the minutes for the current day.
+        # The value that is used is some sort of aggregation call on the
+        # panel, e.g. `sum` for volume, `max` for high, etc.
+        self.current_day_panel = create_current_day_panel(
+            self.fields, initial_sids, initial_dt)
+
+        # Helps prop up the prior day panel against having a nan, when
+        # the data has been seen.
+        self.last_known_prior_values = {field: {} for field in self.fields}
+
+        # Populating initial frames here, so that the cost of creating the
+        # initial frames does not show up when profiling get_history
+        # These frames are cached since mid-stream creation of containing
+        # data frames on every bar is expensive.
+        self.return_frames = {}
+
+        self.create_return_frames(initial_dt)
+
+    def create_return_frames(self, algo_dt):
+        """
+        Populates the return frame cache.
+
+        Called during init and at universe rollovers.
+        """
+        for history_spec in self.history_specs.itervalues():
+            index = index_at_dt(history_spec, algo_dt)
+            index = pd.to_datetime(index)
+            frame = pd.DataFrame(
+                index=index,
+                columns=map(int, self.current_day_panel.minor_axis.values),
+                dtype=np.float64)
+            self.return_frames[history_spec] = frame
+
+    def update(self, data, algo_dt):
+        """
+        Takes the bar at @algo_dt's @data and adds to the current day panel.
+        """
+        self.check_and_roll(algo_dt)
+
+        fields = self.fields
+        field_data = {sid: {field: bar[field] for field in fields}
+                      for sid, bar in data.iteritems()
+                      if (bar
+                          and
+                          bar['dt'] == algo_dt
+                          and
+                          # Only use data which is keyed in the data panel.
+                          # Prevents crashes due to custom data.
+                          sid in self.current_day_panel.minor_axis)}
+        field_frame = pd.DataFrame(field_data)
+        self.current_day_panel.ix[:, algo_dt, :] = field_frame.T
+
+    def backfill_sids(self, sid_states, dt):
+        """
+        backfills data for sids that have entered the universe.
+
+        New sids will not have the data for previous bars, so the data
+        needs to be fetched and populated when they enter.
+        """
+        prior_day_panel = self.prior_day_panel.get_current()
+        # Remove the dropped sids, to prevent stale data.
+        prior_day_panel = prior_day_panel.drop(sid_states['removed_sids'],
+                                               axis=2)
+        for sid in sid_states['removed_sids']:
+            try:
+                del self.last_known_prior_values[sid]
+            except KeyError:
+                # Better to ask forgiveness, than ask permission.
+                pass
+        existing_sids = set(prior_day_panel.minor_axis)
+        sids_to_add = sid_states['new_sids'] - existing_sids
+        if not sids_to_add:
+            # If there are no new sids to add, shortcircuit.
+            return
+        total_sids = sids_to_add.union(existing_sids)
+        # Like at the beginning of the backtest, use a panel to collect
+        # the backfilled values.
+        # This implementation is aggressive/inefficent and gets for *all*
+        # sids in the current universe, instead of merging the data.
+        # Mainly because this was easier than dealing whith the merge logic,
+        # and the rollover occurs at quarter turns, which is relatively rare
+        # compared to the minute frequency.
+        # If universe changes closer to a daily rate, we may need to find
+        # a more efficient solution.
+        new_sid_rolling_panel = create_initial_day_panel(
+            self.max_days_needed,
+            self.fields,
+            total_sids,
+            dt)
+        new_sid_panel = new_sid_rolling_panel.get_current()
+        if self.max_days_needed != 1:
+            populate_initial_day_panel(self.db, new_sid_rolling_panel)
+        self.prior_day_panel = new_sid_rolling_panel
+        # Create a fresh current day panel, now using the new universe.
+        self.current_day_panel = create_current_day_panel(
+            self.fields, new_sid_panel.minor_axis, dt)
+        self.create_return_frames(dt)
+
+    def roll(self, roll_dt):
+        env = trading.environment
+        # This should work for price, but not others, e.g.
+        # open.
+        # Get the most recent value.
+        rolled = pd.DataFrame(
+            index=self.current_day_panel.items,
+            columns=self.current_day_panel.minor_axis)
+
+        for field in self.fields:
+            if field in CLOSING_PRICE_FIELDS:
+                # Use the last price.
+                prices = self.current_day_panel.ffill().ix[field, -1, :]
+                rolled.ix[field] = prices
+            elif field == 'open_price':
+                # Use the first price.
+                opens = self.current_day_panel.ix['open_price', 0, :]
+                rolled.ix['open_price'] = opens
+            elif field == 'volume':
+                # Volume is the sum of the volumes during the
+                # course of the day
+                volumes = self.current_day_panel.ix['volume'].apply(np.sum)
+                rolled.ix['volume'] = volumes
+            elif field == 'high':
+                # Use the highest high.
+                highs = self.current_day_panel.ix['high'].apply(np.max)
+                rolled.ix['high'] = highs
+            elif field == 'low':
+                # Use the lowest low.
+                lows = self.current_day_panel.ix['low'].apply(np.min)
+                rolled.ix['low'] = lows
+
+            for sid, value in rolled.ix[field].iterkv():
+                if not np.isnan(value):
+                    try:
+                        prior_values = self.last_known_prior_values[field][sid]
+                    except KeyError:
+                        prior_values = {}
+                        self.last_known_prior_values[field][sid] = prior_values
+                    prior_values['dt'] = roll_dt
+                    prior_values['value'] = value
+
+        self.prior_day_panel.add_frame(roll_dt, rolled)
+
+        # Create a new 'current day' collector.
+        next_day = env.next_trading_day(roll_dt)
+
+        if next_day:
+            # Only create the next panel if there is a next day.
+            # i.e. don't create the next panel on the last day of
+            # the backest/current day of live trading.
+            self.current_day_panel = create_current_day_panel(
+                self.fields,
+                # Will break on quarter rollover.
+                self.current_day_panel.minor_axis,
+                next_day)
+
+    def check_and_roll(self, algo_dt):
+        """
+        Check whether the algo_dt is at the end of a day.
+        If it is, aggregate the day's minute data and store it in the prior
+        day panel.
+        """
+        # Use a while loop to account for illiquid bars.
+        while algo_dt > self.current_day_panel.major_axis[-1]:
+            roll_dt = self.current_day_panel.major_axis[-1]
+            self.roll(roll_dt)
+
+    def get_history(self, history_spec, algo_dt):
+        """
+        Main API used by the algoscript is mapped to this function.
+
+        Selects from the overarching history panel the valuse for the
+        @history_spec at the given @algo_dt.
+        """
+        field = history_spec.field
+
+        index = index_at_dt(history_spec, algo_dt)
+        index = pd.to_datetime(index)
+
+        frame = self.return_frames[history_spec]
+        # Overwrite the index.
+        # Not worrying about values here since the values are overwritten
+        # in the next step.
+        frame.index = index
+
+        prior_day_panel = self.prior_day_panel.get_current()
+        prior_day_frame = prior_day_panel[field].copy()
+        if history_spec.ffill:
+            first_bar = prior_day_frame.ix[0]
+            nan_sids = first_bar[first_bar.isnull()]
+            for sid, _ in nan_sids.iterkv():
+                try:
+                    if (
+                        # Only use prior value if it is before the index,
+                        # so that a backfill does not accidentally occur.
+                        self.last_known_prior_values[field][sid]['dt'] <=
+                            prior_day_frame.index[0]):
+                        prior_day_frame[sid][0] =\
+                            self.last_known_prior_values[field][sid]['value']
+                except KeyError:
+                    # Allow case where there is no previous value.
+                    # e.g. with leading nans.
+                    pass
+            prior_day_frame = prior_day_frame.ffill()
+        frame.ix[:-1] = prior_day_frame.ix[:]
+
+        # Copy the current day frame, since the fill behavior will mutate
+        # the values in the panel.
+        current_day_frame = self.current_day_panel[field][:algo_dt].copy()
+        if history_spec.ffill:
+            current_day_frame = ffill_day_frame(field,
+                                                current_day_frame,
+                                                prior_day_frame)
+
+        if field == 'volume':
+            # This works for the day rollup, i.e. '1d',
+            # but '1m' will need to allow for 0 or nan minutes
+            frame.ix[algo_dt] = current_day_frame.sum()
+        elif field == 'high':
+            frame.ix[algo_dt] = current_day_frame.max()
+        elif field == 'low':
+            frame.ix[algo_dt] = current_day_frame.min()
+        elif field == 'open_price':
+            frame.ix[algo_dt] = current_day_frame.ix[0]
+        else:
+            frame.ix[algo_dt] = current_day_frame.ix[algo_dt]
+
+        return frame