Ẓaʿāʾin is the plural of ẓaʿīnah. In this context it denotes women travelling in camel litters, sometimes extending to the covered conveyances themselves. It therefore evokes a specific caravan scene rather than unspecified travellers.
For desert journeys, routes, access to water, predawn departure and fitted travelling equipment were practical concerns. Zuhayr transforms them into poetry. Geography and coverings identify the caravan; the verbs of motion make the scene unfold.