Saraveca language

Saraveca is an extinct Arawakan language once spoken in Bolivia by the Sarave. It is said^[1][2] to be the only language with a numeral system based exclusively on five, although quinary systems exist. To some extent this is also an areal feature of other South American languages; many form their numbers 6–9 as "five + one", "five + two" and so on.

Saraveca
Native to	Bolivia
Region	Eastern lowlands
Extinct	2nd millennium
Language family	Arawakan Southern ? Paresí–Xingu Paresí Saraveca
Language codes
ISO 639-3	sar
Glottolog	sara1331
ELP	Saraveca

References

1. Wells, David (1997). The Penguin Dictionary of Curious and Interesting Numbers. Penguin UK. ISBN 978-0-14-026149-3.
2. Encyclopædia Britannica, "Numerals and numeral systems".