The following sentence appeared in an article in the Illustrirte Zeitung of Leipzig in 1845:¹

Er erlernte die zwei gangbarsten der verschiedenen chinesischen Dialekte und, um sich völlig als Chinese zu nationalisiren, ließ er sich unter den chinesischen Stamm Koë aufnehmen, legte auch sofort chinesische Kleidung an.

I want to render this in English, and it is fairly clear. However, I'm having trouble with the clause in bold, since:

• lassen sich can be used so idiomatically; and
• aufnehmen has a very wide range of meaning, and I'm not sure of the correct nuance here.

I have consulted the standard online sources, as well as my big Oxford-Duden dictionary. The best I've got for that at the moment is:

... he affiliated himself with the Chinese tribe of Koë, ...

Have correctly understood the two issues noted above?

_{¹ The article provides an account of the work of Karl Gützlaff.}

The following sentence appeared in an article in the Illustrirte Zeitung of Leipzig in 1845:¹

Er erlernte die zwei gangbarsten der verschiedenen chinesischen Dialekte und, um sich völlig als Chinese zu nationalisiren, ließ er sich unter den chinesischen Stamm Koë aufnehmen, legte auch sofort chinesische Kleidung an.

Here's how it appeared in the original publication:

I want to render this in English, and it is fairly clear. However, I'm having trouble with the clause in bold, since:

• lassen sich can be used so idiomatically; and
• aufnehmen has a very wide range of meaning, and I'm not sure of the correct nuance here.

I have consulted the standard online sources, as well as my big Oxford-Duden dictionary. The best I've got for that at the moment is:

... he affiliated himself with the Chinese tribe of Koë, ...

Have correctly understood the two issues noted above?

_{¹ The article provides an account of the work of Karl Gützlaff.}