Answer:
Portugal is the country that colonized the circled region.
Step-by-step explanation:
The country that is colored with a paler reddish color and is circled on this map is Brazil. Nowadays an independent country, it was not always like that, as its modern-day boundaries and basis for it to become the country that is were set by the colonizers in the past. The country that managed to colonize what is now Brazil was Portugal.
Portugal, during the period of the Great Discoveries, was among the biggest naval powers in the world. For such a small country it had incredible achievements when it came to discovering new areas that were unknown to Europeans, establishing new trade routes, and colonizing territories. The Portuguese marked what is now Brazil as their target for colonization in the Americas and did so with relative ease. They created a huge colony which brought them a lot of wealth, and after the colony was granted independence it actually became the biggest country in South America and one of the biggest countries in the world.