During their 150-year rule, the British favored Tamils and other minority ethnic groups over the majority Sinhalese. After 1947's national elections, the Sinhalese tried to reverse the discrimination, culminating in a quarter-century-long civil war.
When the Brits arrived, the Subcontinent was a patchwork of princely states. When they left centuries later, they divvied it up by religion, prompting mass migration and perhaps a million deaths. Kashmir, which had a Hindu leader and a Muslim majority, has been contested ever since.
Border disputes and ethnic tensions have been rife since 1920, when the British forged modern-day Iraq out of three Ottoman states: Baghdad, Basra, and Mosul. The Brits decamped after a 1958 revolution, but their hellish handiwork lives on.
A British-Egyptian alliance ruled North and South Sudan separately until 1946, when the Brits abruptly changed their minds and decided the two should merge. The north was economically and politically favored over the south, and civil war has been on and off ever since.
As anti-Semitism gained ground in Europe, an influx of Jews complicated land claims, but the Brits—in charge of this former Ottoman territory starting in 1921—flip-flopped on the declaration of Israel as the Jewish homeland and proposed partition, which was rejected by both sides. In 1948 they cut their losses and left it up to the United Nations. Today, a solution is as far off as ever.
Fashioned in 1960 from a British protectorate and an Italian colony, Somalia has been divided against itself ever since. In the 1990s, after decades of civil strife, the government collapsed and the two neighbors declared autonomy.
The West African nation was once two distinct states—officially joined in 1914, but administered by the British separately until independence in 1960. Here, the British favored the south, setting the stage for decades of strife.