Complex sentence: Later he went to Nakhjavan and in 1065-1066 completed his seminal work, the Garshapnama, which he dedicated to Abu Dolaf, the ruler of Nakhjavan.
Split into simpler sentences: Later he went to Nakhjavan and in 1065-1066 completed his seminal work, the Garshapnama. He dedicated this work to Abu Dolaf, the ruler of Nakhjavan.