Jerome, on Gen 25:1

“And Abraham married another wife, named Cetura:”

“(Chapter 25, Verse 1) And Abraham added and took another wife, and her name was Keturah. And she bore him Zimran, Jokshan, Medan, Midian, Ishbak, and Shuah. And Jokshan begot Sheba and Dedan. And the sons of Dedan were Asshurim, Letushim, and Leummim. And the sons of Midian were Ephah, Epher, Hanoch, Abida, and Eldaah. All these were the sons of Keturah. And Abraham gave everything that he had to Isaac. But to the sons of the concubines whom Abraham had, Abraham gave gifts, and he sent them away from Isaac his son, while he was still alive, to the east, to the land of the east. Cetura is interpreted in the Hebrew language as 'joined' or 'bound'. For this reason, the Hebrews suspect that, with a changed name, she is the same as Hagar, who, after the death of Sara, went from being a concubine to a wife. And it seems that the advanced age of Abraham is now being excused, so that he is not accused of indulging in new marriages after the death of his old wife. Leaving aside what is uncertain, we say this: the sons of Abraham born from Cetura, according to Hebrew historians, occupied Troglodytis and Arabia, which is now called Idumea, up to the borders of the Red Sea. But it is said that one of the descendants of Abraham, who was called Apher, led an army against Libya, and there, after defeating the enemies, settled. And his descendants from the name of their ancestor were called Africa. This fact is testified by Alexander, who is called Polyhistor, and Cleodemus, nicknamed Malchus, who retell the barbarian history in Greek. And as for what he says, 'And the sons of Dedan were Asshurim, and Letushim, and Leummim': they think that Asshurim refers to merchants, Letushim to those who work with copper and iron, and Leummim to chiefs, meaning leaders of many tribes and peoples. Others claim that they are called Asurim, that they are Syrians, and that the regions of India have been occupied by most of the sons of Abraham from Keturah.”

Imported from an open dataset — not yet checked against the printed edition.