What made AFSPA withdrawal from the North-East possible?

For nearly seven decades, the Armed Forces Special Powers Act (AFSPA) stood as one of India's most powerful, and at times controversial, security laws, imposed in regions battling insurgency, separatism and armed violence. Union Home Minister Amit Shah recently announced that over 80 per cent of the North-East is already free from AFSPA. More importantly, he announced that the law could be withdrawn from almost the entire North-East region by next year. A historic chapter may be nearing its end. But what exactly is AFSPA? Why was it imposed for so long? What has changed on the ground to make its withdrawal possible?