It has been established that a large chunk of irregular and dangerous migrants leaving from north Africa for Italy do so from Libya, though there are also routes to Italy from Egypt and Morocco, and from Turkey to Greece. Historically, In the 1970s and 1980s, forced and voluntary settlement of nomads, wars in the Sahel, and droughts provoked two types of mobility. First, impoverished (former) nomads and traders, such as the Tuareg, started migrating to work at construction sites and the oil fields of southern Algeria and Libya. Second, with recurrent warfare in the entire Sahel zone, thousands of refugees settled in towns and cities in Libya, Algeria, Mauritania, and Egypt. Such immigration was often tacitly welcomed. In Algeria and Mauritania, for instance, sub-Saharan migrants filled local labor shortages and fitted into policies to revitalize underpopulated parts of the country.

After the 1973 oil crisis, Libya and, to a limited extent, Algeria, witnessed increasing immigration of laborers from their southern neighbors to their sweltering Saharan hinterlands, where oil wells are located but where nationals often refuse to work. Libya rapidly developed into North Africa’s major migration pole. Although most immigrants were Egyptians, large numbers of Sudanese were also allowed to enter. This earlier migration and settlement of (semi-) nomads in Libya and Algeria also set the stage for more large-scale, trans-Saharan migration after 1990, because numerous ex-nomads found new livelihoods in smuggling goods and people across the Sahara.

A 2013 report for the United Nations High Commissioner for Refugees (UNHCR), by Altai consulting, clearly estimates that the cost of getting to Libya varies from about $200 to $1,000 from west Africa, and from about $1,000 to $6,000 from the Horn of Africa. Once they get to this point, subsequent transit by sea runs from a few hundred dollars to a couple of thousand. Immediately they arrive at the coast, the passengers are transported further by either loading them onto rigid inflatable boats with limited fuel and no captain or guide to help them or are herded onto rickety fishing boats which do have a skipper and crew. Ordinarily, the journey from Libya to Italy is a couple of hundred kilometres—less than a day’s sail—but the boats are not necessarily intended to get all the way. Immediately these boats are clear of the Libyan coast, a distress call is made in the hope that the migrants will be picked up either by a passing merchant ship or fishing boat or by the Italian or Maltese coast guards. In cases where the vessel is crewed, the crew members flee or try to pass as migrants, often successfully.

It has been observed that most of these migrants fleeing their homes are mostly young and agile and have been made to undertake this journey because they are fleeing some mixture of war, oppression, civil disorder and poverty. This journey is not often made straight as they stop and work at various places along the route.

According to Italian estimates there are between 500,000 and one million currently in Libya awaiting passage; living conditions are usually bad, but most migrants have no way back to where they came from. Although North Africa is the main route for most of them, there are other migrants from mainly from west Africa and the horn of Africa and. Last year, according to the UNHCR, 31% of arrivals were Syrians, and 18% were fleeing Eritrea. By 2015, it was argued that the flow to Italy is dominated by migrants from the Gambia, Senegal and Somalia. There are routes through the Sahara from both west Africa and the Horn of Africa; there are also some routes along the Mediterranean coast. For many of the communities along the way the traffic in would-be migrants is now a dominant part of the local economy.

Most often the journey is risky because the boats used are old and often of dubious seaworthiness; their crews often abandon them. They are also severely overcrowded. For example, the boat that sank on April 19th was about 20 metres long and carrying more than 900 people, many of them locked below decks.

The UNHCR estimates that 26,165 migrants have reached the shores of Italy this year, a similar number to the 26,644 who arrived in the first four months of 2014. However in the first four months of 2014 only 96 are thought to have died, as opposed to an estimated 1,700 so far this year.