at other sites for centuries thereafter, gradually losing ground to Christianity. At Mardin, believers in the old religion are known from as late as the 18th century. Individuals with names harkening back to ancient Mesopotamia are also attested at Assur until it was sacked for the last time in AD 240 and at other sites as late as the 13th century. Though many foreign states ruled over Assyria in the millennia following the empire's fall, there is no evidence of any large scale influx of immigrants that replaced the original population, which instead continued to make up a significant portion of the region's people until the Mongol and Timurid massacres in the late 14th century. In pre-modern Syriac-language (the type of Aramaic used in Christian Mesopotamian writings) sources, the typical self-designations used are ʾārāmāyā ("Aramean") and suryāyā, with the term ʾāthorāyā ("Assyrian") rarely being used as a self-designation. The terms Assyria (ʾāthor) and Assyrian (ʾāthorāyā) were however used in several senses in pre-modern times; most notably being used for the ancient Assyrians and for the land surrounding Nineveh (and for the city of Mosul, built next to Nineveh's ruins). In Syriac translations of the Bible, the term ʾāthor is also used to refer to the ancient Assyrian Empire. In the sense of a citizen of Mosul, the designation ʾāthorāyā were used for some individuals in the pre-modern period. The reluctance of Christians to use ʾāthorāyā as a self-designation could perhaps be explained by the Assyrians described in the Bible being prominent enemies of Israel; the term ʾāthorāyā was sometimes employed in Syriac writings as a term for enemies of Christians. In this context, the term was sometimes applied to the Persians of the Sasanian Empire; the 4th-century Syriac writer Ephrem the Syrian for instance referred to the Sasanian Empire as "filthy ʾāthor, mother of corruption". In a similar fashion, the term was also sometimes applied to the later Muslim rulers. The self-designation suryāyā, suryāyē or sūrōyē, sometimes translated as "Syrian", is believed to be derived from the Akkadian term assūrāyu ("Assyrian"), which was sometimes even in ancient times rendered in the shorter form sūrāyu. Some medieval Syriac Christian documents used āsūrāyē and sūrāyē, rather than āthōrāyē, also for the ancient Assyrians. Medieval and modern Armenian sources also connected assūrāyu and suryāyā, consistently referring to the Aramaic-speaking Christians of Mesopotamia and Syria as Asori. Despite the complex issue of self-designations, pre-modern