With the Colossus and a connected Peacocks resource the maximum population for the Bantu is 325 (for other nations it's 270). They start with 50 and add another 50 for each Military level researched up to a maximum of 250 (any research after Military Level 4 provides no further increase). The Bantu get a 100% bonus on the population limit.This equals an additional 2.5 population points per Military tech researched. Peacocks, a rare resource, increase the base population limit by 10%, if gathered by a Merchant from the Market.The Colossus wonder increases the population limit by a fixed 50.Military future tech adds no further improvement to this limit.
There are several ways of increasing the limit: All Artillery Weapons and most ships take up 2 population points, all other units 1 population point. It starts at 25 and counts for both military units and civilian units (like Citizens and Scholars). The Population Limit, sometimes population cap or shortened pop cap, is the maximum number of units a nation is allowed to have.