Complex sentence: From December 1988 until OCtober 1990 bis Anfang Oktober 1990 he was the last United States Ambassador to East Germany and after that, from 1991-1994 he was the United States Ambassador to Turkey.
Split into simpler sentences: From December 1988 until October 1990, he was the last United States Ambassador to East Germany and after that. From 1991-1994, he was the United States Ambassador to Turkey.