Complex sentence: For a while Egypt and Syria formed the United Arab Republic (UAR) and when the union was dissolved, Egypt continued to be known as the UAR until 1971, when Egypt adopted the current official name, the Arab Republic of Egypt.
Split into simpler sentences: For a while Egypt and Syria formed the United Arab Republic (UAR). When the union was dissolved, Egypt continued to be known as the UAR until 1971, when Egypt adopted the current official name, the Arab Republic of Egypt.