We will present here an example of agent-based model which permit to simulate a dynamic of settlement of during roman period in south of France, according to the variations of agricultural yields under climate control. The model simulates the impact of yield changes on subsistence and commercial agriculture. Different types of villas and farms (grain farms, vine and olive farms) have been programmed as agents in NETLOGO with a set of parameters (exploited area, number of operators, production, and transport costs, etc...). The values assigned to these parameters derived from the latin agronomic treaties (Caton, Varron, Columelle, etc.) and historical works. In this model, farms and villas disappear when they are no longer profitable or when wheat crops are insufficient to feed farmers. It incorporates an emulation function of the LPJmL agroecosystem model, which allows to produce fast calculations of the potential yields of wheat, vine, and olive according to a reconstruction of climate variations. The first results show a positive impact of the Roman Climate Optimum on the profitability of farms. In particular, they show that climate change has largely changed crop geography and land use, as the cultivated species respond in a different way to temperature and precipitation changes.