A look at ethnic groups in the Indonesian part of Borneo Island, where indigenous Dayak fighters have killed hundreds of people in a week of violence against the Madurese minority.

The Dayaks and ethnic Malays each make up about 40 percent of the population in Borneo's Kalimantan provinces. Ethnic Chinese, holders of much of the region's wealth, make up about 12 percent of the population, and Madurese about 8 percent. 

The Dayaks: 

The word Dayak refers to the largely non-Muslim indigenous peoples who inhabit the interior regions of Borneo. About 2 million strong, the Dayaks are mostly Christian, though many still hold ancient animist beliefs. 

Dayaks often live along rivers in longhouse communities with no more than a few hundred members. Their livelihood has traditionally rested on the cultivation of rice, along with fishing, hunting and logging of rain forests. 

In recent years many Dayaks took jobs in the island's gold, tin and copper mines. 

Before Dutch colonialists outlawed the practice in the late 19th century, the Dayaks had a well-deserved reputation as headhunters. Ancient Dayak tradition holds there is no better symbol of victory than the head of an enemy — and that cutting out the hearts of foes helps destroy the evil believed to live in the organ. 

The Madurese: 

The Madurese, strict Muslims, began arriving in large numbers in the 1960s as part of a government-ordered relocation drive to relieve overcrowding on Madura Island, just off the coast of Indonesia's main island, Java, about 200 miles south of Borneo. 

Now numbering around 100,000, they compete with the Dayaks for space in the lowest echelons of Borneo's economy. Many Madurese resent the Dayak habits of keeping dogs and eating pork — animals shunned in Islam. 

The people of Madura Island are culturally close to the people of Java, site of Indonesia's capital, Jakarta.