The Diocese of Sibu is located on the central part of Sarawak. When it became a diocese in 1986 it covered the Sibu, Mukah, Kapit and Sarikei divisions of Sarawak comprising the towns of Sibu, Kanowit, Mukah, Dalat, Sarikei, Bintangor, Julau, Kapit and Song. It covers an area of 58,542.3 square kilometers or 47 percent of Sarawak's territory. The diocese's population is made up of Chinese, Malays, Ibans, Bidayuhs, Melanaus and Orang Ulu, among others.
The population is dominated by Chinese especially the Fuzhou as well as indigenous Melanau, Malay, and Iban. The district population (per year 2008 census) is 255,000.
There is no known adjective for the people from Sibu, although there have been many unofficial suggestions: Siburian, Sibuian, Sibunite, Sibu-yan - none are officially recognised.
Sibu has a reputation as a rough, frontier town on the riverside. Even today, it is one of the most bustling towns in East Malaysia. It was originally called "New Foochow"after the Foochow immigrants from the Fujian province of China, who settled in Sibu in the early 20th century at the invitation of Rajah Charles Brooke. However, there were many ethnic groups immigrant from China at that time, such as Heng Hua, Hokkien and others. These people brought a lot of positive changes to Sibu town. The new settlement was located next to a small Melanau village that had been established in the 1850s. The first group of Chinese immigrants from Fuzhou, China, led by Pastor Wong Nai Siong, reached Sarawak in year 1900.
With the Rajang River becoming increasingly bustling with economic activity, Sibu served an important role in the Brooke administration as a trading center between the coast and the vast upriver hinterland. Sibu continues to fulfill this role today.
Sibu also has university-level courses offered by United College Sarawak, which has built a campus on the site of the old Sibu airport.
Sibu Jaya, located 25 kilometers away, is being developed as a satellite town. Sibu Airport, built during the World War II, was relocated to its present site in 1994.
Sibu (the seat of the diocese) is a town, and the capital of Sibu District (229.8 square kilometers) in Sibu Division, Sarawak. It is located at the confluence of the Rajang and Igan rivers, some 60 kilometers from the ocean.
Sibu is the main tourist gateway to the Upper Rajang River, with its small towns.
There has been a marked increase in public buildings in recent years. Sibu now boasts the largest town square in Malaysia, and the tallest building in Sarawak - the Sanyan, a newly refurbished waterfront, and a large number of public parks.
There used to be a Sibu Fort, which was built by Rajah Brooke in 1862. The fort was located at Race Course Road. However, it no longer exists now. It was common for the White Rajah to build such forts to stake his territorial claim as well as means of protection.