Image copyright Ahmad Al-Hayshi Image caption More than 45 million people have fled their homes in the last two decades
More than 45 million people have fled their homes in the last two decades.
There are almost two million more refugees than a decade ago.
Many are escaping the war in Syria and others have moved to Africa in search of jobs.
Here are the main factors:
The war in Syria, which has killed more than 470,000 people, has created an unprecedented wave of people fleeing their country.
Many are Syrians fleeing the conflict with relatives or because they cannot find work locally.
The countries neighbouring Syria — Jordan, Lebanon, Turkey and Iraq — and the European Union have received the largest number of refugees.
But the US, Canada and Australia have also taken large numbers.
The decades-long turmoil in Egypt is finally beginning to show some positive signs.
But the country is still struggling to provide for its own citizens.
Government-backed and increasingly popular Islamist groups have tried to exploit discontent with the army-backed government, which has faced mounting pressure from Islamist opposition.
There are now roughly 1.8 million registered refugees and asylum seekers in Egypt. But there are possibly another 2.6 million or more who have not been registered.
Although visas were issued in 2013 to Turks living in Egypt to seek residency, the new government has since suspended the programme.
Two decades after Israeli forces captured the Gaza Strip and the West Bank from Jordan and Egypt, people are again fleeing to Israel and other countries in the region.
The conflict in Gaza between Hamas and Israel, as well as the competing interests of Sunni-Arab states who share a border with the territory, makes the situation particularly volatile.
Jihadists, who once occupied the Palestinian territories, have been fleeing toward more moderate Sunni Arab states.
There are about four million ethnic Iranians living outside Iran. Many have moved to Europe and America to escape a crackdown by the Islamist regime and the ensuing economic hardship.
Prime Minister Recep Tayyip Erdogan has been trying to decrease the number of Syrian refugees in Turkey.
But the Ankara government remains one of the main hosts, which has made it particularly sensitive to any moves to close its borders.
The war in Syria is not the only factor.
Turkey is also dealing with economic difficulties, as seen by its record deficit last year.
Libya’s economy, already a basket case before the civil war, remains in intensive care and is barely able to feed itself.
About 1.1 million people, or about one in every 100 of the country’s estimated 6.5 million people, are thought to be internally displaced.
Fighting between rival militias and among civilians is common, making it difficult for the authorities to control borders.
Before the outbreak of the war in Iraq, less than half of the population was foreign-born, mostly Syrian. But now more than a quarter of the population is foreign-born.
The majority are Muslim Iraqis who have been fleeing sectarian violence. Thousands of people are also foreign workers from countries including Lebanon, Jordan and Turkey, as well as from Syria.
Iraqi authorities took steps in 2015 to register 1.4 million Iraqi refugees but only half of them have complied.
The UN refugee agency estimated in January that there were 5.8 million refugees, and more than 5.4 million people as internally displaced.
Image copyright AFP Image caption Syrians have long tried to reach Europe, mostly to Lebanon, Turkey, Jordan and beyond
The Syrian government has long considered refugees as illegal immigrants and has pressed to expel them.
But there are signs that the regime may be losing control in some regions in Syria.
There are also concerns over food supplies, especially in the crowded camps in Turkey and in Lebanon, where a new wave of Syrians has joined the refugee population.
Lebanon is the only country in the region where a majority of the population is Syrian and there are an estimated 700,000 to 800,000 refugees.
Its prime minister warned in April that the country was running out of land for new refugee camps.
Syria is also not the only source of refugees.
East African countries, such as Kenya, Ethiopia and Uganda, often see some refugees return home, either to Syria or other countries in the region.
The World Bank said in December that the number of refugees in the Middle East had fallen by 18% to 12.3 million between 2015 and 2018.