BuddyPress.org

Oh, hold on.

If you are using BP on WPMU and want to run it on a blog which is not the root blog (root blog is blog_id = 1). See https://codex.buddypress.org/how-to-guides/changing-internal-configuration-settings/ but in your wp-config, add:

define ( ‘BP_ROOT_BLOG’, 2 );

For running BP on blog id 2, for example.