Her children were kept secret, and remained largely unknown until the 20th century.

He was almost unknown in the West until the early 1980s.

I wasn't exactly unknown in the operational areas and until now could be reached without too much trouble.

The largest of these events, and unknown until some extraordinary luck in my recent research, took place on May 1, 1865.

A small community remained unknown until 1976, but it appears that all infrastructure is lost now.

The success of the park was unknown until recent studies.

That fact was unknown to the police until today, the sheriff said.

The breed was quite unknown outside Hungary until the 1970s.

They were unknown to the outside world until the 1950s.

The language was unknown beyond its immediate area until 1990, and is now highly endangered.