The Quadi were a Germanic people during the Roman era, who were prominent in Greek and Roman records from about 20 AD to about 400 AD. By about 20 AD they had a kingdom centred in the area of present-day western Slovakia, north of the Roman border on the Danube river. After probably first settling near the Morava river the Quadi expanded their control eastwards over time until they also stretched into present day Hungary. This was part of the bigger region which had been partly vacated a generation earlier by the Celtic Boii, and their opponents the Dacians. The Quadi were the easternmost of a series of four related Suebian kingdoms that established themselves near the river frontier after 9 BC, during a period of major Roman invasions into both western Germania to the northwest of it, and Pannonia to the south of it. The other three were the Hermunduri, Naristi, and the Quadi's powerful western neighbours the Marcomanni.