What does this sentence mean?

[vv0510_vn]

This article is in the Reading comprehension of my English book, but it makes me a little bit confused. I can't understand it clearly, especially the sentence in red below. Can anyone explain it for me? Thanks.

==============================================
Jim Thomson was a young American when he arrived in Thailand in 1945, two days after the end of World War II. For the next twenty two years, he lived in Thailand, working to revitalize the Thai silk industry, which had all but disappeared. As the founder of his own silk company, he also promoted Thai arts and crafts. Today you can tour the Jim Thomson House in Bangkok, one of the finest examples of traditional Thai architecture in the city.
===============================================

[engee30]

This article is in the Reading comprehension of my English book, but it makes me a little bit confused. I can't understand it clearly, especially the sentence in red below. Can anyone explain it for me? Thanks.

==============================================
Jim Thomson was a young American when he arrived in Thailand in 1945, two days after the end of World War II. For the next twenty two years, he lived in Thailand, working to revitalize the Thai silk industry, which had all but disappeared. As the founder of his own silk company, he also promoted Thai arts and crafts. Today you can tour the Jim Thomson House in Bangkok, one of the finest examples of traditional Thai architecture in the city.
===============================================

...which had [all but = almost] disappeared.
which = the Thai silk industry

[vv0510_vn]

Oh! I see. Thanks a lot!