During the 1960s and 1970s, severe power shortages, strikes and a violent Marxist–Maoist movement by groups known as the Naxalites damaged much of the city's infrastructure, resulting in economic stagnation.[21] The Bangladesh Liberation War of 1971 led to a massive influx of thousands of refugees, many of them penniless, that strained Kolkata's infrastructure.[55] During the mid-1980s, Mumbai (then called Bombay) overtook Kolkata as India's most populous city.