In the 16th century, the Ottomans reinforced their eastern frontier with what they considered loyal Sunni Kurd tribes. They settled Kurdish tribes in these regions and in 1583 Sultan Murad IV "gave huge provinces to the Kurdish tribe of Mokri". According to Aboona, "many regions with numerous Assyrian and Armenian monuments and monasteries became completely populated by the Kurds after Chaldiran," and Kurdish historians wrote that "the land was cleared at this time, its indigenous inhabitants driven out by force". The Kurdish historian Ali al Qurani affirmed that Sarsink had "been an Assyrian town and that the Kurds who settled there were immigrants from Persian Azerbaijan." Phebe Marr noted that 'in the north too, many of the Kurdish tribes of Persia migrated to Iraq'. British traveler James Rich observed in northern Iraq the "rapid influx of Kurds from Persia... and that their advance never ceased". He noted that "some ten thousand families, comprising seventy thousand souls, were constantly moving across the border". Southgate also observed the "rapid advance and settlement of the Kurds from Persia into northern Iraq" around that time. Dr. Grant gave an eyewitness account, he stated: "Beth Garrnae (the region of Arbil-Kirkuk) once contained a large population of Nestorian Christians, they are now reduced to a few scattered villages... Within the last six years the Koords of Ravandoos and Amadia have successively swept over it.." A new epoch began in the 17th century when Emir Afrasiyab of Basra allowed the Portuguese to build a church outside of the city.