The paragraph below began with the past tense but soon switched to present tense (highlighted in bold). I am trying to learn tense consistency. I don't know why such switch is allowed. It's very confusing for me to learn to keep a consistent tense =(
In Banjuh, the capital of Gambia, I met with a group of Gambians. They told me how for centuries the history of Africa has been preserved. In the older villages of the back country, there are old men called griots, who are in effect living archives. Such men memorize and, on special occasions, recite the cumulative histories of clans or families or villages as those histories have long been told. Since my forefather had said his name was Kin-tay (properly spelled Kinte), and since the Kinte clan was known in Gambia, the group of Gambians would see what they could do to help me. I was back in New York when a registered letter arrived from Gambia.
Word had been passed in the back country, and a griot of the Kinte clan had, indeed, been found. His name, the letter said, was Kebba Kanga Fofana. I returned to Gambia and organized a safari to locate him.