Osage (; Osage: Wažáže ie) is a Siouan language that is spoken by the Osage people of Oklahoma. Their original territory was in present-day Missouri and Kansas but they were gradually pushed west by European-American pressure and treaties. Osage has an inventory of sounds very similar to that of Dakota, also a Siouan language, plus vowel length, preaspirated obstruents and an interdental fricative (like "th" in English "then"). In contrast to Dakota, phonemically aspirated obstruents appear phonetically as affricates, and the high back vowel *u has been fronted to . Osage is written primarily with two systems: one using the Latin script with diacritics, and another derived Osage script created in 2006. Osage is among the few indigenous languages in the United States that has developed its own writing system. Language revitalization As of 2009, about 15–20 elders were second-language speakers of Osage. The Osage Language Program, created in 2003, provides audio and video learning materials on its website. The 2nd Annual Dhegiha Gathering in 2012 brought Osage, Kaw, Quapaw, Ponca and Omaha speakers together to share best practices in language revitalization. In early 2015, Osage Nation Chief Thompson Raul Standing Bear announced he would make Osage language immersion a priority. Phonology Osage phonology is quite similar to that of Kansa. But, it preserves many historical alternations that have been leveled out in Kansa; for example, Kansa *u has merged with *i, whereas it is still largely distinct in Osage. Vowels Basic vowels Osage has five plain vowels: These are written . is a high front vowel: like English i in ski. is a high non-back rounded vowel, like California or New Zealand English u in dude. is a half-open front vowel: like English e in bet. is a mid-back rounded vowel: like English o in bolt. is an open back vowel: like English a in bra. varies between central and front, , and frequently unrounds to . It is especially far front following a velar obstruent and when it is near a front vowel with no intervening obstruent. It most commonly conflates with following ð and n. Usually in fast speech, the /a/ is pronounced . This assimilation occurs after a stressed syllable, or at the end of a word. For example: 'cow', 'this one'. Nasalized vowels There are three vowels that carry this feature: . It is quite common for nasalized to become a nasal and vice versa.