Oglethorpe and a group of colonists had been sent from England to colonize, and to make a place for debtors to start a new life. In 1733, they arrived on the coast of Georgia and later settled at current day Savannah.
But before it was Savannah, it was known as Yamacraw Bluff, and this was the land of Tomochichi and his tribe. Of course, there was a language barrier between Oglethorpe and Tomochichi, so Mary Musgrove, who had spoken both languages, translated between the two.
Tomochichi had given Oglethorpe permission to settle at Yamacraw bluff because he had wanted to be friends with the English. This lead to the both of them trading goods with each other, and to Oglethorpe and Tomochichi becoming good friends.