Final answer:
The Spanish claimed most of the territory south of the Georgia colony in the 1750s, using mission villages and political presence as mechanisms for establishing control in the buffer zone against British colonies.
Step-by-step explanation:
The entity that claimed most of the territory south of the Georgia colony in the 1750s was Spanish Florida. This area was strategically important as it served as a buffer zone between the British colonies and the Spanish in Florida, and the British in Georgia were particularly interested in maintaining a garrison province to defend against potential Spanish intrusions.
Georgia, being the last of the original thirteen colonies to be established, was an outpost of British power in the south, and was continuously contested by the British and Spanish through alliances, trade, and warfare. The Spanish maintained their claim to the area through a chain of religious mission villages among the Native Americans and by establishing a political presence.