If Pakistan's authorities possess the will and the means, their declaration that all irregular foreign migrants and refugees must leave the country by November 1st or be expelled will force one of the biggest human movements in South Asia’s troubled modern history. The great bulk of Pakistan’s illegal settlers are Afghans: about 1.7m of the 4.4m Afghans in Pakistan are believed not to have the right papers. Driven out of Afghanistan by decades of war and chaos, they will return to a broken country. Earthquakes have just flattened swathes of the western province of Herat. Afghans who fled the Soviet invasion in 1979 have been away so long they lack connections. Others were born in Pakistan. Many of the 600,000 reckoned to have fled from Afghanistan after the Taliban seized power in August 2021 will have reason to fear for their lives.