The Avars, mysterious horse-riding warriors who helped hasten the end of the Roman Empire, dominated the plains between Vienna and Belgrade, Serbia, for more than 2 centuries. Then, they vanished without a trace...The Avars had no written records. Grave goods and historical accounts suggest they dominated the plains of modern-day Hungary soon after their arrival in Europe about 1500 years ago. They interred their elites in massive burial mounds, surrounded by weapons, and finely decorated gold and silver vessels. They were often buried with horses and riding equipment. (The earliest stirrups in Europe are from Avar graves.)...The first Avar burials...