Although little is known for definite about the history of Qasr al-Abd it is widely believed to have been built by a Tobiad notable,Hyrcanus of Jerusalem, head of the powerful Tobiad family and governor of Ammon. Credence for this theory is gained from the fact that the Hebrew name 'Tuvya' or 'Toviyya' (Tobias) is engraved but in a more Aramaic script) above the adjacent burial caves of Iraq al Amir (which share their name with the nearby village). In another of these caves there is a carving of a lioness sheltering a cub at the palace.
According to a local legend, Tobiad was a commoner who fell in love with the daughter of a nobleman. When he asked for her hand in marriage, the nobleman said that Tobiad could only have her hand if he built the so-called "Castle of the Slave." After completing the castle, the nobleman had Tobiad killed as he did not want his daughter marrying a commoner.
It is known that the structure was originally surrounded by a large excavated reflecting pool, leading the first-century AD Jewish historian Flavius Josephus to suppose that this was a moat and the building a fortress. However, more recent evidence for the building's original function being as a country pleasure palace has been presented by the contemporary Israeli archaeologist Ehud Netzer. It has also been suggested that the site was in fact intended to serve as a mausoleum of the Tobias family, although it was never completed.
The name Qasr al Abd can be translated as Castle of the Slave or Servant, a title which may refer to Hyrcanus himself, who, as governor, was a "slave of the people". The biblical Book of Nehemiah mentions "Toviyya, the Servant, the Ammonite" (2:10). According to Josephus, Hyrcanus left Jerusalem after losing a power struggle, and established his residence east of the Jordan, apparently on the ancestral lands of the Tobiad dynasty. The area was then a border zone between Judea and Arabia, and Josephus mentions that Hyrcanus was in
