Rural commons in East-Africa have historically played key socioeconomic and environmental sustainability. Despite growing interest in this arena, there are still surprisingly few studies that examine rural customary management of pastoral communities in East Africa. This is striking given that this region is an exemplary area for pastoralism and thus ideal for communal systems such as commons. Deficient studies and political support in this area could be linked to widespread prejudice of branding pastoralism as perilous to the environment. We set out to conduct a study to examine and test pastoralists' customary norms that underpin environmental sustainability/ unsustainabity of pastoral commons focusing on Mwanda-Marungu, in Taita hills, Kenya where the first author originates and brought up as a pastoralist up to the age of 24. Through ethnographic approaches and semi-open interviews to 193 respondents conducted in 2019-2021 during water and pasture stress during the dry months of July-October, we examined whether customary governance of Mwanda-Marungu would offer sustainable model that conforms to the IUCN's Other Effective Area-Based Conservation Measures (OECMs). Our study showed that pastoral communities in this area have been developing inventive measures for generations that improve good management and ecological protection. These may be tied to the principles of OECMs which contests the misconception about pastoralism.