In this study the development of the population in Caybagi (Kotur) basin, current population status and distribution of population are analyzed. Caybagi basin is located in eastern part of Turkey next to the Iranian border. The research field (basin) is completely located in Saray District of Van Province. Study area includes 21 villages and two hamlets. The population of the research field (Caybagi basin) in 1935 was 1884. The population was increased steadily until 2007 and reached 16619. After 2007 till today's population decreased 15684. In the search field, the human sex ratio is high at total population. However, this ratio in some settlements is lower. Analysis of age groups of population in Caybagi basin, 40,4% population younger than 14 years of age, 56,8 % working age, and 2,8 % elderly age. Dependency rate is (76%) in the basin which is well higher than the country average rate (46 %). Currently in Saray District over the 6 years-of-age, literacy rate is % 92. In 2014, the population density rate is 100 in Turkey. In Caybagi river basin density rate is 21. It is well below from country's level. Orenburc, Beyarslan and Karahisar are differentiated from other rural settlements by having more population.