The Fertile Crescent: Iraq, Syria, Lebanon, Israel/Palestine
1 CE At the beginning of the study period, this region was divided between the Roman and Persian (Iranian) empires, with the Romans holding what today is the settled region of Syria, Lebanon, and Palestine while the Persians (Iranians) held Iraq. The deserts were inhabited by the Nabatean Arabs, who maintained trade routes and built cities at the periphery of the desert. For the next six centuries, the region was largely immune to the migrations that flooded Roman Europe and political boundaries remained stable, although the Romans did grab Iraq briefly during the 2nd century. At this time, Jewish communities populated by people taking advantage of freedom of movement and security in the Roman and Parthian (Persian/Iranian) Empires, existed all over the Roman and Persian/Iranian world, Still, in CE 1 the center of Jewish culture was their ancestral homeland of Judea. If your ancestors were Iraqi or Iranian Jews in CE 1800, their ancestors probably lived in those same regions in CE 1. Whatever their religion, if your ancestors lived anywhere in the Roman part of the fertile crescent (Syria/ Palestine) in CE 500, their ancestors could have been anywhere in the Roman Empire in CE 1. Likewise if they were in the Persian part (Iraq).
Two revolts in the first and second centuries deprived the Jews of their cultural center. Refugees went not only to Roman and Iranian lands, but to Arabia (particularly Yemen) and Ethiopia. If your ancestors are Ethiopian, or Yemeni Jews, their ancestors were probably both there and in Judea in CE 1. Remember, at this time, laws charting Jewish heritage through the mother were new and weakly enforced. Many Jews married locals in their new homes. Don't assume that all of your ancestors from this period were Jewish. Also note: Most of the Jews who remained in Judea after the second (Bar Kochba) revolt gradually lost their Jewish identity, especially after Judea became part of the Muslim Umma.
7th century: The expansion of the Muslim Umma brought a new ruling class to the region - Arabs from the Arabian peninsula. Their empires, the Ummayad and Abbasid Caliphates, stretched from Spain through Iran. Throughout the fertile crescent, Arabic became the common language. As a result, if you had ancestors in the Fertile Crescent in 1000 CE, their ancestors could conceivably have come from anywhere in the Umayyad or Abbasid Caliphates in CE 500.. NOTE: People changed religions and switched languages extensively following the Arab conquests. If your ancestors in 1800 were Arabic speakers from this region, it would be very naive to think that your ancestry is exclusively Arabian. If you are Palestinian Arab, for instance, you probably had Jewish ancestors living in Palestine in 1 CE.
11th Century: By this time, the Abbasid state was in decline, and many of its regions had gone independent. Shortly after AD 1000, the Seljuk Turks, a Central Asian nationality, migrated into Iran, the fertile crescent, and Anatolia, converted to Sunni Islam, and founded the Seljuk Empire, which politically succeeded the Abbasid Caliphate. Even though the Seljuks didn't hold onto the Fertile Crescent for long, if your ancestors in 1490 were are of aristocratic Sunni Muslims from this region, it is conceivable that they had Turkish ancestors in Central Asia in AD 1000. Note that the Turks, themselves, originated in Mongolia a few centuries earlier, so your probable Turkish ancestors would have lived there, also, in CE 500.
12th Century: The first of a series of crusades hit Syria, Lebanon and Palestine. The crusaders were Western European Catholics, most were French. The first crusade resulted in the establishment of small "crusader states" on the Eastern margin of the Mediterranean. There ensued much trade and transfer of genes. If your ancestors were in Syria, Lebanon, or Palestine in 1490 CE, or if you have anomolously Western-European looking features, you almost surely had ancestors living in France in CE 1000. Especially if your ancestors were Catholic.
13th Century: The Mongol expansion under Mongke Khan overran Iraq, which lived under Mongol rulers for nearly century. Iraq and Iran were a particular focus of interest for the Mongols because they enjoyed the highest standard of material culture in their empire. Thus traffic between Iraq and the Mongol heartland was intense. Thus, if you had ancestors in Iraq in CE 1490, their ancestors could have lived anywhere in the Mongol Empire in CE 1000.)
14th century: The fertile crescent was divided among several Arab dynasties. One, the Mamluks, deserves special note. "Mamluk" is Arabic for "servant." The Mamluks were originally a slave corps of soldiers, officers and administrators who managed to recognize that they wielded the real power in their land and take over. Although based in Cairo, they exerted control over much of the fertile crescent. Genetically, they are interesting because the slaves from whom they were descended came mostly from the Balkans - Albania, Greece, Bosnia, etc. or from the Turkic peoples of southern Ukraine and Central Asia. Thus if you had aristocratic Arab ancestors in the Fertile Crescent in 1490 CE, their ancestors might have come from anywhere in the Eastern Mediterranean, Egypt, the Balkans, and southern Ukraine in 1000 CE.
16th Century: Takeover by the Ottoman Turks. These were a remnant of the Seljuks who ruled a small area in Northwest Anatolia which they managed to turn into the nucleus of a great empire. Genetically, the Ottomans were not like their Central Asian Seljuk forebears, having intermarried with the local Greek-speaking Anatolian population. The Ottomans ruled a cosmopolitan Empire that encompassed Greece, Bulgaria, former Yugoslavia, Albania, Romania, and Hungary. The Ottomans had a practice of drafting non-Muslim children into public service, raising them, and training them for the army or for high administrative posts. Because of this, if your ancestors in 1800 were of known Turkish or aristocratic Arab descent, their ancestors could be from anywhere in the Ottoman Empire in 1490.