An advantage can be that its position enables it to trade well with others. It's located at the edge of a desert so caravans with merchants commonly went through Timbuktu to recuperate which meant that goods and capital was flowing through the city. In addition, it is close by to the river which enables people to reach various parts of Africa if needed.
A disadvantage can also be that it is close to the desert as such harsh terrain is not well suited for things like agriculture or similar things although there was agriculture in Timbuktu. In addition, during the height of the empire, the land was surrounded from all sides by different tribes or nations who often attacked the empire and took wealth from it, Timbuktu being often attacked.
