by the time that Attila came of age during the reign of his uncle Ruga, to the point that Nestorius, the Patriarch of Constantinople, deplored the situation with these words: "They have become both masters and slaves of the Romans". Campaigns against the Eastern Roman Empire The death of Rugila (also known as Rua or Ruga) in 434 left the sons of his brother Mundzuk, Attila and Bleda, in control of the united Hun tribes. At the time of the two brothers' accession, the Hun tribes were bargaining with Eastern Roman Emperor Theodosius II's envoys for the return of several renegades who had taken refuge within the Eastern Roman Empire, possibly Hunnic nobles who disagreed with the brothers' assumption of leadership. The following year, Attila and Bleda met with the imperial legation at Margus (Požarevac), all seated on horseback in the Hunnic manner, and negotiated an advantageous treaty. The Romans agreed to return the fugitives, to double their previous tribute of 350 Roman pounds (c. 115 kg) of gold, to open their markets to Hunnish traders, and to pay a ransom of eight solidi for each Roman taken prisoner by the Huns. The Huns, satisfied with the treaty, decamped from the Roman Empire and returned to their home in the Great Hungarian Plain, perhaps to consolidate and strengthen their empire. Theodosius used this opportunity to strengthen the walls of Constantinople, building the city's first sea wall, and to build up his border defenses along the Danube. The Huns remained out of Roman sight for the next few years while they invaded the Sassanid Empire. They were defeated in Armenia by the Sassanids, abandoned their invasion, and turned their attentions back to Europe. In 440, they reappeared in force on the borders of the Roman Empire, attacking the merchants at the market on the north bank of the Danube that had been established by the treaty of 435. Crossing the Danube, they laid waste to the cities of Illyricum and forts on the river, including (according to Priscus) Viminacium, a city of Moesia. Their advance began at Margus, where they demanded that the Romans turn over a bishop who had retained property that Attila regarded as his. While the Romans discussed the bishop's fate, he slipped away secretly to the Huns and betrayed the city to them. While the Huns attacked city-states along the Danube, the Vandals (led by Geiseric) captured