In June 2012, I saw resplendent herds of cattle along the Sudan-South Sudan border. We toiled together along muddy roads as cloudbursts announced the definitive end of the dry season. The rain seemed to erupt from the very air around me, as if it had grown tired of its liquid burden. It was difficult to see more than five metres ahead.

What I could see were those cows. In Pariang County, on the southern side of the border, one particularly proud herder drove his cows ahead of him, as we slipped and stumbled in the mud. The small brown cows of the Baggara Arabs, out of place in South Sudan and struggling in the rain, mixed with the large black bulls of the Mbororo, their skin slick and glistening, and jostled with the prized cattle of the Nuer, their horns decorated with tassels, and with whom the young cattle-guards stole whispered conversations, as if with illicit lovers...