The nations which make up Central Asia are five of the former Soviet republics: Kazakhstan, Kyrgyzstan, Turkmenistan, Tajikistan and Uzbekistan, which have a total population of about 76 million. Afghanistan is not always considered part of the region, but when it is, Central Asia has a total population of about 122 million (2016); Mongolia and Xinjiang is also sometimes considered part of Central Asia due to its Central Asian cultural ties and traditions, although geographically it is East Asian. Most central Asians belong to religions which were introduced to the area within the last 1,500 years, such as Sunni Islam, Shia Islam, Ismaili Islam, Tengriism and Syriac Christianity. Buddhism, however, was introduced to Central Asia over 2,200 years ago, and Zoroastrianism, over 2,500 years ago.