Karen prefixation is in large part of late origin, as shown by the general lack of correspondences between Karen and TB prefixes. Pwo θwa <*swa ‘tooth’, TB *s-wa; Pwo and Sgaw θwi<*swi ‘blood’, TB *s-hwiy; are isolated instances of agreement. Sgaw has a fairly extensive set of prefixes, sometimes alternating with initial consonant clusters, as in lε ‘exchange’, kǝlε∼klε ‘change, mix, combine’, Pwo lai ‘exchange, mix’ (in comp.), TB *lay; Sgaw wɔ ‘surround, encircle’, kǝwɔ ‘circle, surround; to be circular’, kwɔ (k-wɔ) ‘encircle, bend into a circle or curve; circle, curve’, Pwo wą ‘encompass; to be circular’, khwą (kh-wą) ‘to be circular’, TB *hwaŋ. Prefixed k- is especially common before l-, as shown by the following series:

Karen also has discordant (with TB) prefixed k- in certain other roots:

Pwo and Sgaw kwa (k-wa) ‘ax’; TB *r-wa.

Sgaw kǝha? ‘phlegm’; TB *ha·k ‘hawk, gag, choke’.

Pwo kǝshą, Sgaw kǝshɔ ‘elephant’; B tshaŋ.

Karen has prefixed p- for TB *b- and *m- in the following pair of roots:

Pwo phla, Sgaw pǝla∼pla ‘arrow’; TB *b-la.

Pwo phle, Taungthu pre, Padaung ble, Sgaw pǝle∼ple ‘tongue’; TB *m-lay∼*s-lay.

The former root might be submitted as evidence for the reconstruction of TB *bla rather than *b-la ‘arrow’ (cf. n. 314).