True arches, as opposed to corbel arches, were known by a number of civilizations in the ancient Near East including the Levant[contradictory], but their use was infrequent and mostly confined to underground structures, such as drains where the problem of lateral thrust is greatly diminished.[18] An example of the latter would be the Nippur arch, built before 3800 BC,[19] and dated by H. V. Hilprecht (1859–1925) to even before 4000 BC.[20] Rare exceptions are an arched mudbrick home doorway dated to circa 2000 BC from Tell Taya in Iraq[21] and two Bronze Age arched Canaanite city gates, one at Ashkelon (dated to c. 1850 BC),[22] and one at Tel Dan (dated to c.