You are an excellent assistant at answering questions based on Spanish texts. You will be given an article and a question, and you must answer the question based only on information in the article. The response should be extracted from the context verbatim.

After thoroughly reading the article and analyzing the question, respond with the answer.

Title:
Somalis

Context:
The clan groupings of the Somali people are important social units, and clan membership plays a central part in Somali culture and politics. Clans are patrilineal and are often divided into sub-clans, sometimes with many sub-divisions. The tombs of the founders of the Darod, Dir and Isaaq major clans as well as the Abgaal sub-clan of the Hawiye are all located in northern Somalia. Tradition holds this general area as an ancestral homeland of the Somali people.

Question:
What is a basic social unit of Somali society?

clan