Although there are many social, economic, and political similarities between the Javanese and Sundanese, differences abound. The Sundanese live principally in West Java, but their language is not intelligible to the Javanese. The more than 21 million Sundanese in 1992 had stronger ties to Islam than the Javanese, in terms of pesantren enrollment and religious affiliation.
Although the Sundanese language, like Javanese, possesses elaborate speech levels, these forms of respect are infused with Islamic values, such as the traditional notion of hormat (respect - knowing and fulfilling one's proper position in society). Children are taught that the task of behaving with proper hormat is also a religious struggle - the triumph of akal ('reason') over nafsu ('desire'). These dilemmas are spelled out in the pesantren ('islamic boarding schools'), where children learn to memorize the Quran in Arabic. Through copious memorization and practice in correct pronunciation, children learn that reasonable behavior means verbal conformity with authority and subjective interpretation is a sign of inappropriate individualism.
Although Sundanese religious practices share some of the Hindu-Buddhist beliefs of their Javanese neighbors - for example, the animistic beliefs in spirits and the emphasis on right thinking and self-control as a way of controlling those spirits - Sundanese courtly traditions differ from those of the Javanese. The Sundanese language possesses an elaborate and sophisticated literature preserved in Indic scripts and in puppet dramas. These dramas use distinctive wooden dolls (wayang golek, as contrasted with the wayang kulit of the Javanese and Balinese), but Sundanese courts have aligned themselves more closely to universalistic tenets of Islam than have the elite classes of Central Java.
As anthropologist Jessica Glicken observed, Islam is a particularly visible and audible presence in the life of the Sundanese. She reported that "the calls to the five daily prayers, broadcast over loudspeakers from each of the many mosques in the city of Bandung, punctuate each day. On Friday at noon, sarong-clad men and boys fill the streets on their way to the mosques to join the midday prayer known as the Jumatan which provides the visible definition of the religious community (ummah) in the Sundanese community." She also emphasized the militant pride with which Islam is viewed in Sundanese areas. "As I traveled around the province in 1981, people would point with pride to areas of particular heavy military activity during the Darul Islam period."
It is not surprising that the Sunda region was an important site for the Muslim separatist Darul Islam rebellion that began in the 1948 and continued until 1962. The underlying causes of this rebellion have been a source of controversy, however. Political scientist Karl D. Jackson, trying to determine why men did or did not participate in the rebellion, argued that religious convictions were less of a factor than individual life histories. Men participated in the rebellion if they had personal allegiance to a religious or village leader who persuaded them to do so.
Although Sundanese and Javanese possess similar family structures, economic patterns, and political systems, they feel some rivalry toward one another. As interregional migration increased in the 1980s and 1990s, the tendency to stereotype one another's adat in highly contrastive terms intensified, even as actual economic and social behavior were becoming increasingly interdependent.