Why did the Komuz language Gule become extinct?

The Gule language (also known as Anej), a member of the Komuz branch of the Nilo-Saharan languages, became extinct because its speakers shifted to using Arabic for their daily communication.12

This process of language shift occurs when the domains of language use overlap to the extent that one language becomes obsolete. In the case of Gule, as with several other endangered Nilo-Saharan languages, speakers transitioned toward a different primary language—in this instance, Arabic—for their everyday needs.1