Complex sentence: After his release he becomes director of the arts section of the Academy of Science, Arts and Literature from 1978 to 1981, but then he joins the opposition party Somali National Movement and stays in Ethiopia from 1981 to 1991.
Split into simpler sentences: After his release he becomes director of the arts section of the Academy of Science, Arts and Literature from 1978 to 1981. He joins the opposition party Somali National Movement and stays in Ethiopia from 1981 to 1991.