Targum for Numbers 12:1

And Miriam and Aharon spake against Mosheh words that were not becoming with respect to the Kushaitha whom the Kushaee had caused Mosheh to take when he had fled from Pharoh, but whom he had sent away because they had given him the queen of Kush, and he had sent her away.

And Miriam and Aharon spake against Mosheh about the Kushaitha whom he had taken. But observe, the Kushite wife was not Zipporah, the wife of Mosheh, but a certain Kushaitha, of a flesh different from every creature: whereas Zipporah, the wife of Mosheh, was of a comely form and beautiful countenance, and more abundant in good works than all the women of her age.