Proto-MSA

*ṯ̣a(h)r - on, over (Kogan 2015:575)

The original anatomical meaning is completely lost throughout this group. Semantically similar prepositional use of reflexes of *ṯ̣a(h)r- is admittedly attested in a few other Semitic languages (SED I No. 284). (Kogan 2015:575)

PS
*ṯ̣ahr- - back (SED I No. 284; Kogan 2011: 217)

Mehri
ḏ̣ār - on, over (ML 86)
Jibbali
ḏ̣ér - on, over (JL 50)
Soqotri
ṭᵃhar - 1. on, above; 2. in addition, besides (LS 200; CSOL I 684; CSOL II 617; Naumkin et al. 2015a:90)

men ṭᵃhar ‘above’:

hímaˁk bíľeʰ teḥarɛsímin men ṭᵃharénhi ‘I heard something rustle above me’ (CSOL I 10:1)