The voiceless velar fricative [x] was voiced to [ɣ] before voiced stops [b,d,g] (but not, apparently, before [ɟ]). Thereafter the sound developed as [ɣ], disappearing while lengthening the preceding vowel (SD/422).

This changed occurred before [ɣ] vanished, and was therefore probably early. Since it did not apply to the palatal voiced stop, it likely occurred after most palatals became sibilants [s] or [z].