Wikipedia isn't Indian source. Keturah is mentioned in Jewish sources. Arabs know about her and her name is also written in Arabic on the webpage, but Arabs largely ignored her and her descendants.
Keturah was one of Abraham’s wives. The Rabbis describe her as a woman of virtue, for which she was worthy of being joined to Abraham.
jwa.org
'Genesis 25-6 relates that Abraham sent the sons of Keturah away from Isaac “eastward, to the land of the East.” He told them: Go as far eastward as you can'
As for Shajra, we have them too. My dad couldn't stop talking about them until I started doing research. Shajra doesn't explain how we are proud Biharis with ancestries linked to Nalanda and Pataliputra which produced the Maurya empire and the Lions of Faith emblem of India.