Explanation:
Lee Kuan Yew's reign as the Prime Minister of Singapore lasted from June 5, 1959, to November 28, 1990. He served for over 31 years, making him one of the longest-serving leaders in modern history. After stepping down as Prime Minister, he remained influential in Singaporean politics as Senior Minister and later Minister Mentor until his retirement in 2011. He passed away on March 23, 2015.