Situation in which kinship is tracked through the mothers family.

That situation is called Matrilineality.

A matriline is a line of descent from a female ancestor to a descendant  in which the individuals in all the generations are mothers – in other words, a "mother line".

Within matrilineality there are some systems to be considered:

so you know what happened be fore you were alive

explanation:

swahili is an extremely rich and complex civilization, a set of ethnic groups articulated by a language and a series of cultural elements that fuse the african traditions, islam and indian culture. this growth was largely a result of the indian ocean trading network that brought in not just man-made riches, but also religious ideas, specifically islam, which had a significant impact on the local culture. furthermore, the development of the swahili language gave a common cultural unity to the people.