[Picture: Obelisk of Theodosius, Constantinople] After Theodosius died, the Western half of the empire was overrun and conquered by tribes of German nations, but the Eastern part still remained, and emperor after emperor reigned at Constantinople, ruling over the Greek cities as before; but there were savage tribes of the Slavonian race who settled in Thrace, and spread over Thessaly.  They were called Bulgarians, and used to send marauders all over the country to the south, so that they were much dreaded by the Greeks, who had long forgotten how to fight for themselves.