For most of the twentieth century, people had assumed that the "caste system" in Bali was a direct result of Indian influence that came with the Hindu religion. However, anthropologists now wonder if the caste system in Bali was always there but with different names. The reason for this is that anthropologists have now began to look at other Austronesians--mainly Samoan and Hawaiian societies--and saw remarkable similarities with Bali. In many ways, Balinese and Hawaiian societies mirrored each other very closely.
We know that in the case of Samoan and Hawaiian societies there was a strong class division that developed without any influence from other foreign civilizations. In the case of Hawai`i in particular, by the time of Captain Cook's voyage in 1778, the Hawaiian class system resembled Balinese caste system. In Bali, while it is called a caste system, the classes do intermingle and there is some upward social mobility under certain circumstances. However, there is still difference to rank and this rank caste comes from a genealogical relationship with a god. This is not the case in India where it is a true "caste" system meaning that there is no upward social mobility. A person of the Dalit or Untouchable caste can be a billionaire but he or she will never be able to marry someone of the Brahman caste or to be anything except a Dalit. In the case of Bali, there is some ways to improve your caste standing, mainly through intermarriage.
This was also the case of Hawai`i. While the ali`i or nobility was the top class, they could intermarry with someone of a lower class. There is the famous story of `Umi-a-Liloa who was the son of an ali`i and commoner but was able to become king due to his personal charisma and due corruption (both politically and spiritually) of the king, his half-brother, at the time. In other words, in Austronesian class systems, there is some flexibility. On the other hand, Dr. Stephen Oppenheimer wonders if perhaps it was Austronesians who influenced early Indian society and brought with them to India their notions of class divisions.
In Bali, there are four main castes or varna: Sudras (peasants); Wesias or Vaishyas (merchants); Satrias or Kshatriyas (warriors and nobility); and Brahman (priests). According to Balinese themselves, the varnas simply modified the existing social order. Each caste has a particular dialect though this is disappearing in public as more people have adopted Bahasa Indonesia as means to speak to people of various classes without offending them. Among the Brahman, the language used is called "High Balinese" which is old Javanese mixed (Kawi) with Sanskrit--somewhat similar to the language used in the "Laguna Copperplate" found in the Philippines. This language is also used as the language of temple ceremonies. There is also a "Middle Balinese" which is a language that can be used between the different classes but this sometimes troublesome as some terms may have a different meaning between people of the same class and therefore may lead to some offense. Thus, Bahasa Indonesia has become a neutral language of communication.
In certain parts of Bali, mainly in the Aga (non-Hindu Balinese, literally meaning "original") villages of Tenganen and Trunyan, there is also another social system. This social system is divided into three main class: peasants, nobility, and priests. The Aga system is very similar to the Hawaiian system. The Hawaiian social system also hadthe same three classes--nobility or ali`i, kahuna or priestly, and the maka`ainana or commoners--though periodically there was another extremely small social sub-class known as the kauwa. The kauwa was akin to the alipin of the Philippines meaning while both terms are translated as "slave", they had rights and were regarded as extensions of a nobleman's household. However, in Hawai`i this class of people was extremely small--small enough that no European explorer noticed them, Hawaiian mythology does not mention them, and they were eventually abolished in 1810. Normally in Hawai`i, a person would become a kauwa if they were in debt or had lost a war which means that the kauwa were actually drawn from the nobility itself since in Hawai`i--like in Bali--only nobles were allowed to carry weapons and to fight in wars. This could explain why there was no explanation in Hawaiian mythology.
In both Bali and in Hawai`i, the class systems have today largely become simply symbols of the past. In the case of Hawai`i, it was due to the Hawaiian religion being abolished under Premier Ka`ahumanu in 1819 and later with the American take-over in 1893. With Bali, the Dutch colonial experience largely enforced the class system as the Dutch found it easier to control thesudra--though many Balinese refused to submit and to collaborate with the Dutch and there were several mass suicides as late as 1908. Later on, with the democratization of Balinese society after Indonesian independence, the rise of Dadias, and Christian missionaries trying to convert the Balinese, the class system became less enforced. Nowadays, the Brahman are only ones who still retain some of their traditional role. Some Balinese, however, worry about the Brahmans becoming too influenced by India and there are movements to try to retain the distinctive Austronesian-ness of the Balinese Hinduism.
Another aspect of the social system is kinship. In Bali, there are two types of kinship: public kinship; and private kinship. The private kinship is sometimes called the "Hawaiian kinship" or the "Generational kinship" by anthropologists. In old Hawai`i, family relations depended on what generation you were born into. For example, uncles, aunts, and parents in old Hawai`i were all called makua (parent) because they were of the same generation. Likewise, your first cousins may refer to you as their brother or sister because you were both born in the same generation of the family line. Your second cousins (even if they are older than you), however, may refer to you as a makua since you are above them genealogy-wise. Of course with the adoption of Western family ties, this was replaced with the European model.
In the public kinship system, all Balinese belong to various Dadia. A dadia is a kinship relation where several families (sometimes consisting of several thousand people) are bound together in a clan or block because of a common ancestor. Traditionally, the dadia was important because of marital relationships. It was preferred that people marry within the same dadia and during times of trouble, an entire dadia was bound to help each family member out including in warfare. Likewise, under this system, there are no orphans as every member of a dadia would be obligated to help that child and adoptions within a dadia used to be common--like with the Hawaiian system of hanai. The dadia members also normally lived close to each other, share the same family shrines (gede), share in planting and harvesting of crops, participate in the same ceremonies and attended the same temples. Today, dadia are important politically because they are voting blocks and some say a source of corruption. A Balinese politician would try to court dadia family heads in order for ensure that the entire dadia would vote for him or her. Likewise, when a Balinese politician is elected, one of his or her first acts would be to ensure spoils to the dadia that voted for him.
With Hawaiians, there was a concept similar to the dadia called `alaea which for the most part was a clan composed of the commoner class. However, there has not been too much research on this aspect of Hawaiian society since anthropological research tends to be centered around the ali`i since there's more resources. In addition, one can argue that organizations (particularly the so-called "ali`i societies") like Ka Mamakaua or the Daughters and Sons of Hawaiian Warriors (photo below of a Ka Mamakaua ceremony from the 1930s) and the Order of Kamehameha are forms of dadia.
In regards to the Balinese dadia--though in Mindanao, you will find something similar among T'boli, the Tausugs, and especially the Maranao (which they sometimes call agakhan). One can also wonder if the barangay (town or canoe) system with the Tagalogs also had originally operated like the dadia. In addition, the dadia seems to also have striking similarities with the iwi (normally translated as tribe) of the Maori of Aotearoa-New Zealand and the way certain Samoan fale (houses) operate. This seems to suggest that the dadia is something indigenous to various Austronesian societies.