Migration patterns in Pakistan include movements from northern mountainous regions, western highlands, and eastern deserts to the more populous Indus plains. Key drivers of migration have been the development of Punjab's canal colonies in the early 1900s, partition between India and Pakistan in 1947, and several Indo-Pakistani wars which caused waves of refugees. More recently, conflict in Afghanistan has led to many Afghan refugees settling in Pakistan, while illegal immigration from Bangladesh and internal rural-to-urban migration have also significantly impacted Pakistani society and infrastructure. Remittances from international emigration, especially to the Gulf and UK, now constitute a major part of Pakistan's economy.