Tajikistan (pronounce /təˈdʒɪkɨstæn/ or /təˈdʒiːkɨstæn/; Tajik: Тоҷикистон, pronounced [tɔʤikɪsˈtɔn] or [tɒːʤikɪsˈtɒn]), officially the Republic of Tajikistan (Tajik: Ҷумҳурии Тоҷикистон) is a mountainous landlocked country in Central Asia. Afghanistan borders to the south, Uzbekistan to the west, Kyrgyzstan to the north, and China to the east. Most of Tajikistan's population belongs to the Tajik ethnic group, who share culture and history with the Persian peoples and speak the Persian language. Once part of the Samanid Empire, Tajikistan became a constituent republic of the Soviet Union in the 20th century, known as the Tajik Soviet Socialist Republic (Tajik SSR).