The main occupation of the people in the area on the map is most likely to be

Based on the geographic features shown on the map, it is most likely that the main occupation of the people in the area is farming. The map shows a river, which indicates a reliable source of water for irrigation and other farming needs. Additionally, the area appears to have relatively flat and open land, which is suitable for agriculture. While fishing could also be a possibility due to the presence of the river, it is less likely since the map does not show any significant bodies of water beyond the river that would support a fishing industry. Lumbering and mining are also less likely as they typically require specific types of terrain and resources that are not evident on the map.