Malaysian tourist arrivals from Brunei, which saw a growth of 13.5 per cent during the period, trails Singapore, with 3.22 million arrivals; Indonesia, with 630,419; and China, with 493,249.
In March alone, Malaysia had 126,338 arrivals from Brunei, an increase from the 125,786 visits in the same month last year.
China ousted Brunei from the third position it held at end-2012, when 1.255 million visitors to Malaysia made it the third biggest tourism market.
Brunei's full-year count for 2012 was up 1.5 per cent from the previous year, when Malaysia saw 1.23 million visits from Bruneians.
In terms of its share of the Malaysian tourism pie, Brunei has kept its contribution at 5 per cent of total arrivals to Malaysia.
Brunei, a country with around 400,000 people, is surrounded by Malaysia's state of Sarawak, and there are four immigration posts between the two: Brunei-Miri, Brunei-Limbang, Limbang-Temburong, and Temburong-Lawas.
A report from Travel Daily News, an online news portal, said the sultanate holds the lion's share of the tourist arrivals in Sarawak, at 63 per cent in January to May this year. According to the report, Brunei's 673,622 visits for the period made up the largest number of international arrivals.
A study done by Mark Grieves, principal of BerSaMa Jaya Education and Management Sdn Bhd, last year indicated that Bruneians contributed about 5 per cent of the country’s tourism revenue in 2011.
Based on Grieves’ calculations, the average Bruneian travels to Malaysia two or three times a year and spends about $1,000 (Bt31,200) each trip.