This is a small people native to Latvia, living in on the northern tip of the 'peninsula' between the bay of Riga and the Baltic sea. They are only 250-300 people today in Latvia, and only 11 worldwide speak the language as their mother tongue. Livonian is a Finno-Ugric language that was codified into a written standard only in 1935. The middle white stripe seems to be narrower than the stripes above and below, as in the Latvian national flag.
Nothing is said about the symbolism or when the flag dates from.
The Livonian flag was approved at the first meeting of the Livonian Association on April 2, 1923. The flag's colours were chosen because of their close relationship with everyday life that most Livonians led. Blue symbolises the sea, white the sandy beaches characteristic of the area the Livonians inhabit, and green the forest. We may have been confused because it survives only as a second language of some dozens of Latvians, all of them getting on in years. It is in fact a Finno-Ugric language which seems to be on the brink of extinction.