Before Abraham, did any people group know the true God?
No, before Abraham no people group knew the true God. Until God called Abraham, all peoples had only pagan gods. With Abraham's call, he received knowledge of Jehovah, which passed through Isaac, Jacob, and the twelve tribes, so Israel alone had knowledge of the one true God during the period of the ancients.
Les explains that prior to Abraham's call, every people group knew only false gods; the true God was not known among them. When God called Abraham, Abraham gained knowledge of Jehovah, and that knowledge was passed on through Isaac, Jacob, and the twelve tribes. Consequently, Israel alone, during the period of the ancients, had a knowledge of the one true God. All other peoples had nothing but pagan gods—often female goddesses, mythological gods, frogs, animals, the sun, or the moon. This background explains Daniel's words to the pagan king that there is a God in heaven who reveals secrets and makes known what shall be in the latter days.