Final answer:
Since independence from Great Britain in 1948, Sri Lanka's government has primarily been led by two political parties: the United National Party (UNP) and the Sri Lanka Freedom Party (SLFP), with newer parties and coalitions also gaining control in recent years.
Step-by-step explanation:
Since its independence from Great Britain in 1948, Sri Lanka's government has principally been controlled by two major political parties. The United National Party (UNP), founded in 1946 before independence, and the Sri Lanka Freedom Party (SLFP), founded in 1951. These parties have often been at the forefront of Sri Lankan politics either separately or as part of broader political alliances. Following independence, the UNP was the dominant force for the first few decades, helming the government's affairs. The SLFP, representing more socialist and nationalist ideologies, alternated in power mostly from the 1960s onwards, sometimes leading leftist coalitions. In more recent political history, newer parties and alliances, including coalitions led by these two parties, have gained control, reflecting the dynamic nature of Sri Lanka's political landscape.