Sabi is one of the problematic cases in the proposed Bantu subclassification because its languages contain many stem innovations also found in narrow Mashariki and, in some cases, specifically in the Kaskazi branch. Two explanations are offered: borrowing from Mashariki languages or inheritance from a common earlier Mashariki-related ancestor.

The passage favors a historical setting of repeated language shifts in southeastern Central Africa. In eastern Zambia, a Kaskazi substratum is proposed beneath the Sabi languages spoken across the region. This interpretation connects present linguistic patterns with earlier Kaskazi-affiliated populations.

The initial Sabi expansion is correlated with the spread of the Lwangwa archaeological tradition since about 1000 A.D. That tradition is said to overlay the Kalambo culture of the preceding thousand years, which is attributed to Mwika-Rungwe or other peoples with Kaskazi affiliations.