Vietnam ), officially the Socialist Republic of Vietnam, is a country in Southeast Asia and the easternmost country on the Indochinese Peninsula. With an estimated 96.2 million inhabitants as of 2019, it is the 15th most populous country in the world. Vietnam shares its land borders with China to the north, and Laos and Cambodia to the west. It shares its maritime borders with Thailand through the Gulf of Thailand, and the Philippines, Indonesia and Malaysia through the South China Sea. Its capital city is Hanoi, and its most populous city is Ho Chi Minh City, also known by its former name of Saigon. Archaeological excavations indicate that Vietnam was inhabited as early as the Paleolithic age. The ancient Vietnamese nation, which was centered on the Red River valley and nearby coastal areas, was annexed by the Han Dynasty in the 2nd century BC, which subsequently made Vietnam a division of Imperial China for over a millennium. The first independent monarchy emerged in the 10th century AD. This paved the way for successive imperial dynasties as the nation expanded geographically southward until the Indochina Peninsula was colonised by the French in the mid-19th century. Modern Vietnam was born upon the Proclamation of Independence from France in 1945. Following Vietnamese victory against the French in the First Indochina War, which ended in 1954, the nation was divided into two rival states: communist North and anti-communist South. Conflicts intensified in the Vietnam War, which saw extensive US intervention in support of South Vietnam and ended with North Vietnamese victory in 1975. After North and South Vietnam were reunified as a communist state under a unitary socialist government in 1976, the country became economically and politically isolated until 1986, when the Communist Party initiated a series of economic and political reforms that facilitated Vietnamese integration into world politics and the global economy. As a result of the successful reforms, Vietnam has enjoyed a high GDP growth rate, consistently ranked among the fastest-growing countries in the world. It nevertheless faces challenges including poverty, corruption, inadequate social welfare and a poor human rights record, including increasing persecution of religious groups and human rights advocates and intensifying restrictions on civil liberties. By 2010, Vietnam had established diplomatic relations with 178 countries. It is a member of such international organisations as the United Nations , the Association of Southeast Asian Nations , the Asia-Pacific Economic Cooperation forum, and the World Trade Organization .