Visit http://bit.ly/1AKu9Jy for a printable version of this map. THE HOPING If you set out on a journey pray that the road is long --ZBIGNIEW HERBERT You could hear them from miles away. They went tprrr! tprrr! and they went jet jet jet! and they went jot jot jot! and they went ay, shht, shht, oy, trrrrrr, ''uh, ''uh! Repeating with proprietary virtuosity the calls their ancestors had used to talk to their own herds since the dawn of time. As if they journeyed not simply across distance but across eras and dragged with them through the land grooved with prehistoric cow paths all the cattle and all the herders who had laid tracks here before. You could almost make out all of them in the low scarf of shifting laterite dust, cowboys and ghosts of cowboys driving true and phantom herds on an ageless migration that stretched forever. The Fulani and their cows tramped along the edge of the bone-white savannah, restless slatribbed wayfarers weaving among slow cattle just as slatribbed. Nomads chasing rain in the oceanic tracts of the Sahel.

The cowboys wore soiled blue robes that luffed in the wind like sails, and their gait flowed smooth and footsure. Each step stitched the waking earth with a sound smoothed by millennia of repetition, a sound of sorrow and hope and loss and desire: the sound of walking. They whistled and laughed and hurled their clubbed staffs underhand at the cows that were too hesitant or too distracted or out of step and they called "Girl! Shht! " and "Die! Die, bitch!" to such cows, but never in anger. They filled the soundscape with the chink of hooves and staffs upon filaments of shale, with yips and ululations, with incessant banter about cows and women and pontifications about God and swagger about migrations past. They moved in tinny bubbles of bootleg music that rasped from the cellphones they dangled on lanyards from their necks. Some had strapped to their chests boomboxes they had decorated with small mirrors, like disco balls. Their music said go on, go on, go on, go on, go on, in the same iambic beat as the songs of the Kel Tamashek camel riders of the Sahara, the Turkoman goatherds of the Khorasan, the horsemen of the Kazakh steppes. Music made for walking and cowbells.

Music made out of walking and cowbells. Their herds fell together and drifted apart and even when the cattle drive swelled to many thousand head, the Fulani always knew which cows belonged to whom. They seared lines and dots and crosses into the hides of their cattle with sickle-shaped branding irons, but these hieroglyphics mostly were of no need to them because they recognized their livestock and the livestock of others from the serrated silhouette of the herd, from the way dust billowed in its wake, from the particular gait of the bulls. You learned such knowledge somehow. "Those are Afo''s cows, Papa." "No they aren''t." "How can you tell?" "That''s just how it is." "But how can you tell?" "When I see cattle, I know.

" -- Oumarou Diakayat squinted at the procession of cattle and cattle drivers filing into the sunrise. He had risen in the cool blue predawn from the wide reed pallet he shared with his wife, Fanta, their youngest son and daughter, and two small grandchildren, and washed from a small plastic kettle and prayed while most of the camp still slept. In the modest manner of his generation he had wrapped his indigo turban three times around his head and under the gray stubble on his narrow chin and across his thin mouth, in which a few teeth still remained, and dragged his millet-straw mat out of the cold shadows of the hut. Then day crashed into the Sahel in a crescendo of birds. A rooster crowed once and right away clouds of tiny passerines in twilit shrub let loose a delirious trill. Starlings shrieked the world''s oldest birthsong: alive, alive, alive, alive. A kingfisher warbled. The sun hurtled upward red and elliptic from beyond the sparse scrublands, grazed the low umbrella crowns of acacias, slowed down, and hung glaring in the fierce African sky.

Oumarou sat attentive and quite like a bird himself in the canted light of that July morning, with his knees drawn and a blue-checkered fleece blanket wrapped shoulder to toe around his tall and rawboned frame, and watched the herds pass. By the time the sun rose a palm above the treeline, his family would roll up their mats, pilfer the best thatch and rope from their shelters, pile calabashes and gunnysacks of blankets and clothes onto donkey carts, and join the other pilgrims ambling off from the Sahel''s most coveted pasturage to allow farmers a turn with the land. -- Oumarou''s dry-season grazing grounds lay in the fecund seasonal swamplands in the crook of the Niger''s bend, in central Mali. The Fulani called the region the bourgou. Bourgou was hippo grass, Echinochloa stagnina , the sweet perennial semiaquatic species of barnyard grass that grew on the plains from late summer till winter''s end, when the anastomosing stream of the Bani River flooded the Inner Niger Delta. Hippo grass shot its spongy blades up to nine feet out of the wetlands. Its rhizomes floated. It was a drifter, like the Fulani.

Cows went wild for it. The Diakayats had arrived in the bourgou in January, after the rice harvest. Oumarou and his sons and nephews and grandnephews had raised their domed grass huts in a slightly swerving line of six beneath a few contorted thorn trees on a strip of dry land that bulged out of a fen so deep that the cows had to swim to return to camp from pasture. The thorn trees had fingered the soft wind of early winter with feathery peagreen leaves. By July the island was a cowtrodden knuckle barely manifest on an enormous spent plateau. The fen was a foul sike, fragmented and not ankle-deep. All about, the oldest continental crust in the world lay bare, its brittle rusted skin ground to red talc by cattle and the dry harmattan winds of February and the cruel spring heat. The three thorn trees that flanked Oumarou''s hut had no more leaves, and in the dusty naked branches agama lizards with orange heads rotated their eyes and pressed up and up in a laborious Triassic mating dance.

To the northeast, the millet fields of slash-and-burn farmers smoked white against dark gray rainclouds that refused to break. The rain was late. Oumarou had not heard the planetary-scale metastory of the most recent global warming. He had not heard much about the planet at all. He had not even heard about Africa. He could not read, did not listen to the radio. He took bearings by other coordinates calibrated in other ways, brought into existence billions of years before the Earth itself. He sought counsel from the stars.

For centuries the Fulani had aligned the annual movement of their livestock from rainy-season to dry-season pasture and back again with the orderly procession across the sky of twenty-six sequential constellations. Each signified the advent of a windy season, of weeks of drizzle or days of downpour, of merciless heat or relentless malarial mosquitoes that danced in humid nights. But for decades now the weather had been chaotic, out of whack with the stars. The rainy season had been starting early or late or not arriving at all. Oumarou was searching for the promise of rain conveyed across millions of light-years, and he could not reconcile the cycle. In this part of the Sahel, the first week of June was the brief season the Fulani called the Hoping, when people looked at the sky expecting rain any day. This year the Hoping had stretched into two excruciating weeks, then three, then four. Oumarou''s cows hung deflated humps to the side and let down little milk.

Milk made up most of the old man''s diet. He was nauseous with hunger. "Three things make a man live a long and healthy life," he would repeat over a succession of disappointing dinners of bland millet-flour porridge with sauce of pounded fish bones. "Milk, honey, and the meat of a cow that has never been sick." Honey was a rare treat in the bush. As for beef, that was a conjecture, a hypothesis. The Fulani very seldom ate meat, and when they did, it usually was goat or lamb. No Fulani would readily slaughter a healthy cow.

-- Oumarou freed an arm from his blanket and paced off the sky to the sun with a narrow hand. Half a palm''s width. A flock of birds burst out of a low shrub, chirped, circled, settled again. The uninterrupted horizon quivered with birdsong, lizards'' click-tongue, the whimper of goats, the hoof-falls and lowing of moving cows. Eternal sounds. Ephemeral sounds. Three more fingers and the cows would be gone. Time to pack.

Oumarou looked at Fanta, his wife, his fellow rambler, who now stood by his side listening to the faraway herds also. "Ready?" he said. Oumarou''s restlessness dated back to the Neolithic, to the time when a man first took a cow out to graze. It was an outsize brown cow that stood six feet front hoof to shoulder and bore a pair of forward-pointing, inward-curved horns such as the ones that eventually would gore tigers and bears in the coliseums of Rome. The last of her undomesticated tribe, a female wild aurochs, would die of disease or old age or hunger or loneliness in the Jaktorw forest in Poland in 1627. Around 10,000 BC, ancient humans began to encourage the Bos primigenius to stay close. How? Maybe they used salt to entice the massive ruminants, as people did in the twenty-first century with the wild mithans of the Assam hills, with northern reindeer. Or maybe, like the Diakayats did on cattle drives, they simply sweet-talked the aurochs into sticking around.

" Ay , ay , girl!" One way or another, sometime in the early Holocene a colossal proto-cow fe.