You can start with this website http://nigeria.usembassy.gov/ A letter of invitation is usually advised. They may also need to show strong ties to their country, such as family, a job, home, a bank account.
Quick Answer. Over one billion Muslims live in Asia, which makes it the continent with the highest Muslim population. Indonesia is the country with the largest Muslim population, with 209 million people. Continue Reading.
However, the Middle East-North Africa region has the highest concentration of Muslims of any region of the world: 93% of its approximately 341 million inhabitants are Muslim, compared with 30% in sub-Saharan Africa and 24% in the Asia-Pacific region. Muslims make up a majority of the population in 49 countries around the world.