‘your native language or tongue’ is B2 in the English Vocabulary Profile with the meaning: ‘the first language you learn.’ For example:
Now, they speak English but it‘s not their native language,
they‘d rather not speak English.
A collocate search for _APPGE native language|tongue in COCA:
1 LANGUAGE 566
2 THEIR 412
3 TONGUE 300
4 ENGLISH 80
5 SPEAK 53
6 SPEAKING 28
7 SPANISH 23
8 SPOKE 20
9 SPEAKS 16
10 LEARN 11