Can a sitemap index contain other sitemap indexes?

Question

I have a bi-lingual website with a sitemap index for each language that links to several different sitemaps (one for videos, one for static content, and one for articles). I would like to introduce another sitemap that links the sitemap indexes, so I could link that sitemap in the robots.txt in the root and wouldn't have to have one robots.txt for each language.

Is that valid? Or is there a simpler solution to my problem?

Answer 1

Yes, you can have a sitemap index containing references to other sitemap indexes [source], as long as they're all on the same domain.

Each individual sitemap index can include up to 1,000 references to another <sitemap>. If you need to reference more than that, create multiple sitemap indexes and submit each one.

Each individual sitemap can include up to 50,000 page references. If you need more than that, split them across multiple sitemaps.