The Byzantine-Bulgarian conflict reached its apex in 1003, when Hungary became involved. Since the beginning of the 9th century, the Bulgarian territory had stretched beyond the Carpathian Mountains as far as the Tisza River and the middle Danube. During the reign of Samuel, the governor of these northwestern parts was duke Ahtum, the grandson of duke Glad, who had been defeated by the Hungarians in the 930s. Ahtum commanded a strong army and firmly defended the northwestern borders of the Empire. He also built many churches and monasteries through which he spread Christianity in Transylvania.