Nicaraguan Sign Language (ISN)
Nicaraguan Sign Language (ISN) first emerged in the 1970s when deaf children were brought together in schools in western Nicaragua. Prior to the establishment of these schools, there was no Deaf community and deaf children were linguistically isolated from one another. They used home signs and manual gesture at home with their families and friends.
Schools were opened for the deaf children in the 1970s. These deaf children gathered together for the first time and developed their communication system. Speech instruction in Spanish along with fingerspelling was the method of education. However, outside classes, these children developed and acquired a signed language. Hearing teachers were not aware of this language being developed.
A vocational school was opened for these deaf students in the 1980s. Younger children, who had acquired language from the first generation of older students, communicated in a more complex language. Since the mid-1980s, researchers and linguists studied the emergence of this language.
McNeill, David. "Gestural precursors to linguistic constructs: how input shapes the form of langauge." Language and Gesture. Cambridge University Press. PP 358-
You may also be interested in Martha's Vineyard Island Sign Language.Plains Indian Sign Language.