It was not always this dry. During the African Humid Period, between roughly 15,000 and 5,000 years ago, a vast freshwater body called Lake Suguta filled this basin, at times brimming over its northern edge to spill into Lake Turkana. Then the rains failed. Around 8,000 years ago the lake began to retreat, its surface dropping some 250 metres until almost nothing remained. What you walk across today - the Suguta Mud Flats, a flat floor about 300 metres above sea level - is the bed of that lost lake, baked hard and pale. The valley's bones tell an older story still: exposed basalts, tuffs, and ash record waves of volcanic eruption stretching back more than four million years, when the Rift was still tearing itself open along this seam.

At the valley's northern end, Lake Logipi clings to life. It is shallow - three to five metres at most - and intensely saline, fed in the dry season by hot springs that bubble up warm and mineral-laden from below. Those bitter waters would poison most living things, but they nourish cyanobacteria and plankton, and that thin green soup feeds flamingos. They gather here by the tens of thousands, a drifting pink haze against volcanic black, one of the most improbable spectacles in East Africa. In the wet season a seasonal stream, the Suguta River, briefly conjures the temporary Lake Alablad onto the flats before the sun erases it again. Water arrives, water vanishes. The valley keeps only what its springs can hold.

Stand on the Losiolo Escarpment near Maralal and the Rift opens beneath you, the wall dropping some 2,000 metres to the valley floor in one of the most dramatic views in all of Kenya. From above, the Suguta looks serene. Up close it is anything but. The terrain is harsh enough, and remote enough, that it has long served as a refuge for Pokot and Turkana cattle raiders, who know its ravines and waterless distances better than any outsider. Police have treated the region as a no-go zone, wary of an environment that favours those who already live within it. The Barrier Volcano seals the valley off from Lake Turkana to the north; the active cone of Namarunu pushes in from the west. It is a landscape that does not invite, and rarely forgives.

In November 2012 the valley's reputation turned tragic. A large police operation set out near Baragoi to recover livestock stolen from Samburu herders, reportedly taken by a Turkana group - a routine cattle dispute that escalated catastrophically. The officers, many of them young and inexperienced, were ambushed by raiders who held every advantage of ground and knowledge. Forty-two policemen and reservists were killed, and more than fifty firearms lost. It remains one of the darkest single days in the history of Kenya's police service. The men died in country that has swallowed travellers for millennia, undone not only by gunfire but by heat, distance, and an unforgiving terrain that the raiders called home and the officers did not.