On this day, 35 years ago, May 22, 1990 (April 28, 1990 in the lunar calendar), northern and southern Yemen were unified. On May 22, 1990, the Yemen Arab Republic and the People's Democratic Republic of Yemen officially declared their reunification and established the Republic of Yemen. Arab Yemen and Democratic Yemen are located in the southwest of the Arabian Peninsula and were originally one country in history. During the Saba Dynasty in Yemen, Malib Gulba created the most prosperous Arab civilization and was known as the green Yemen and the cradle of Arab civilization. At the beginning of the 16th century, Yemen became a dependency of the Turkish Ottoman Empire. In 1839, British colonialists occupied Aden. In 1914, Britain and Turkey signed the Anglo-Turkish Treaty, dividing Yemen into northern and southern parts. In 1918, the north broke away from Turkish rule, declared independence, and established the Kingdom of Mutakilia. In 1962, the Yemeni "Free Officers" group overthrew the Badr Dynasty and established the Arab Republic of Yemen. Under the influence of northern independence, anti-British armed struggle also broke out in the south in 1963. In 1967, Britain was forced to agree to the independence of South Yemen and establish the People's Republic of Yemen. In 1970, the People's Republic of Yemen was renamed the People's Democratic Republic of Yemen and announced the path of socialism. After the independence and founding of North and South Yemen, the issue of reunification began to be put on the agenda. However, due to different political and economic systems, as well as interference and influence from external forces and issues left over from history, relations between the two countries have been tense and armed border conflicts have occurred twice. Later, under the mediation of brother Arab countries, the two sides reconciled, signed the "Kuwait Agreement" and the "Sana'a Communique", and established a Joint Constitution Drafting Committee to formulate a constitution for a unified Yemen. In 1981, the two heads of state met in Aden and established the Supreme Council of Yemen composed of the two heads of state and the Unified Ministerial Council attended by the two prime ministers. In January 1982, both sides adopted the "Unified Constitution (Draft)". Two Supreme Council meetings were held in 1983 and 1984. In 1986, a bloody coup occurred in Aden, and former national leaders fled to Sana'a. Relations between the two sides cooled again and the reunification process stalled. Since 1988, southern and northern Yemen have accelerated the pace of reunification. In May 1988, Yemeni Arab President Saleh and General Secretary of the Socialist Party of Democratic Yemen Bid signed an agreement in Sana'a to free transit of north and south residents and jointly develop oil and mineral resources in the border area. Since then, official and people-to-people exchanges between the two countries have been frequent. In November 1989, the two heads of state signed the "Aden Agreement" and approved the "Unified Constitution (Draft)" drafted by both parties in 1981. In March 1990, the two sides held a cabinet contact meeting on reunification issues, adopted a unified 1990 budget draft, 45 bills and 153 relevant provisions, as well as the unified organizational structure, and authorized the two prime ministers to make decisions on the exchange rates of the two currencies. On April 22, the two heads of state signed the "Unity Agreement (Draft)" in Taz, Arab Yemen, formally announcing the unification terms for the first time. On May 21, the South and North Yemeni parliaments made final arrangements on the issue of reunification: they named the Republic of Yemen, the capital Sana'a, and determined May 22 as the birth date of the Republic; Saleh was elected as the first president, making Arabic the national language and Islam the state religion. After reunification, Yemen has an area of more than 500,000 square kilometers and a population of nearly 12 million. There is abundant rain in the north, which is suitable for agricultural development. The south is close to the ocean, is rich in aquatic resources, and has the convenience of boats. Coupled with the considerable reserves of oil, natural gas and other mining resources in the north and south, Yemen's comprehensive national strength has been greatly strengthened. But the good times will not last long. On May 21, 1994, on the eve of the fourth anniversary of the reunification of northern and southern Yemen, the leader of southern Yemen, Bid, issued a "Message to the People" through Aden Radio and Television, announcing that the south would secede from the Republic of Yemen and establish the "Democratic Republic of Yemen." This means that the reunification of the north and the south has come to an end, division has emerged again, and a war of war has spread again.