Old Javanese or Kawi (poet, कवि) is the oldest attested phase of the Javanese language. It was spoken in the eastern part of what is now Central Java and the whole of East Java, Indonesia. As a literary language, Kawi was used across Java and on the islands of Madura, Bali and Lombok. It had a sizable vocabulary of Sanskrit loanwords but had not yet developed the formal krama language register, to be used with one's social superiors that is characteristic of modern Javanese.
While evidence of writing in Java dates to the Sanskrit Tarumanegara inscription of 450 CE, the oldest example written entirely in Javanese, called the Sukabumi inscription, is dated 25 March 804 CE. This inscription, located in the district of Pare in the Kediri Regency of East Java, is actually a copy of the original, dated some 120 years earlier; only this copy has been preserved. Its contents concern the construction of a dam for an irrigation canal near the river Śrī Hariñjing (now shortened to Srinjing). This inscription is the last of its kind to be written using Pallava script; all consequent examples of Old Javanese are written using Kawi script.
Old Javanese was not static, and its usage covered a period of approximately 500 years – from the Sukabumi (Kediri, East Java) inscription until the founding of the Majapahit empire in 1292. The Javanese language which was spoken and written in the Majapahit era already underwent some changes and is therefore already closer to the Modern Javanese language.
The most important shaping force on Old Javanese was its Austronesian heritage in vocabulary, sentence structure and grammar that it shared with its sister languages in Southeast-Asia.
The Indian linguistic influence in Old Javanese language was almost exclusively Sanskrit influence. There is no evidence of Indian linguistic elements in Old Javanese other than Sanskrit. This is different from, for example, the influence of Indian linguistic in the (Old) Malay language.
Sanskrit has had a deep and lasting impact on the vocabulary of the Javanese language.