Milestones of Indonesian History and Languages
1.6 to 1.2 millions years ago: Fossils of the first Java man (called Pithecanthropus erectus Java Soloiensis) was found in Central Java island (Sangiran) by Dutch anthropologist, Eugene Dubois in 1891. Another oldest similar fossils were found and known as Peking man and East African man. What language they used is not known and reported, probably they used sign language.
78 AD: Prince Aji Caka (an Indian migrant) established the first known kingdom called Java Dvipa (Swarna Dvipa) in Central Java island of Indonesia. Java-kawi language was used, and Java script was first introduced (20 java script/letters of ha, na ca, ra, ka, da, ta, sa, wa, la, pa, da, ja, ya, nya, ma, ga, ba, tha, nga). Chinese chronicles of 132 AD described the existence of diplomatic ties between Java-Dvipa and China).
200AD: Kutai Kingdom in Kalimantan island was reported under the king of Mulawarman.
400 AD: Buddhist kingdom, Tarumanegara was established in West Java Island. In this region, people now speak Sunda language, which may be rooted back from this era.
425 AD: Another Buddhist kingdom (Srivijaya) in South Sumatra Island was build. A Chinese buddhist pilgrim, I Tsing, visited Srivijaya in 671 AD and studied the Sanskrit language and Buddhism, together with local well-known philosophy scholars: Sakyakirti, Dharmapala and Vajabudhi. People in this region (in Palembang and Jambi, now ) speak Palembang language (a dialect of present Indonesian language).
732 AD: King Sanjaya (in Cailendra kingdom, or first Mataram kingdom) in Central Java build BOROBUDUR temple (the biggest Buddhist temple in the world and become one of the world 7 wonders together with Great Wall of China and Egyptian Pyramid, etc. Now, it becomes UNESCO historical & archeological site). It took 55 years to build the temple in that period (till King Samaratungga's rule). The remains still exist now, and become tourist spot near Yogyakarta city.
790 AD: King Cailendra in Central Java reigned up to Cambodian region.
929 AD: King Empu Sendok build a kingdom in East of Java.
975 AD: King Udayana established a kingdom in Bali island.
1135 AD : King Jayabaya ruled the well-known period of Kediri Kingdom, and many literary works were produced, including the Javanese version of Indian Mahabharata by Mpu (saint) Sedah and his brother Mpu Panuluh.
1292 AD: Majapahit Kingdom, also in east Java (near Surabaya, now) was first ruled by Prince Wiiaya. The Moghul emperor, Kubilai Khan (China) attempted to invade Majapahit.
1331: King Hayam Wuruk ruled Majapahit Empire, and it became the most powerful kingdom in the history of Indonesia. It covered territories beyond the borders of the present archipelago, such as Champa (North Vietnam) and Kampuchea in the north, and the Philippines in the east, and Madagaskar island in the west (this is one of the reasons why Tagalog language in Philippines nowadays is very similar to Javanese language). King Hayam Wuruk and his premier Gajah Mada, succeeded in uniting the whole archipelago under the name of Dwipantra. During this golden period of Majapahit many literary works were produced. Among them was "Negara Kertagama", "Arjuna Wiwaha", and "Ramayana" by the famous author Mpu Prapancha (1335-1380).
1345: Samudera Pasai kingdom (in Aceh now) became the first Moslem kingdom in Indonesia. Some Arabic language was used in a certain degree, especially in religious schools.
1505: King Sultan Trenggono build the first Moslem kingdom in Java, called Demak. Many other small kingdoms were established in other islands to fight against Portugese. Each kingdom introduced local language as a way of communication and unity.
1509: Portugese came to Indonesia, and ruled many parts of Indonesia until around 1600. Roman script was first introduced in Indonesia.
1602: Dutch under VOC (Verenigde Oostindische Compagnie) or Dutch East India Company first came to Indonesia, and ruled Indonesia till 1945. Dutch language was used in the govermental offices.
1811-1816: Indonesia was under British with Thomas Stanford Raffles as Lieutenant Governor General of Java, during the Napoleonic wars in Europe when Holland was occupied by France. English had also influence to each island language (especially Java language).
1942-1945: Japan was in Indonesia, and Japanese language also had some influence to local languages.
1945: Indonesia gained Independence from Dutch, and Indonesian language was officially used as national language to unite people all over the islands, who speak different island language in different island (In Indonesia nowadays, all primary school children from 1st year up to 3rd year grade are taught in local island language, and starting from 4th year they learn Indonesian language, as national language. Without Indonesian language, they can not understand each other).
Just for your information: in 1994, a computer language, called Java was created in USA by Sun Microsoft Systems, and well popularly used for Internet applications (and also used in Indonesia, of course).