The route can be broken up into three legs with stops in Celendín and Leymebamba, the two best bases for exploring the area's quiet Andean villages and ancient ruins. Or, if you're short on time, it can be done in one spectacular 12-hour haul. The section between Celendín and Chachapoyas has quite a bad reputation, and many guidebooks advise travelers to take other routes, especially in the rainy season. Two and a half years ago, however, the road got an overhaul and what is often still listed as a 15-hour bus ride now only takes 8 on good, dry roads.

Several bus companies (all located near the 4th cuadra of Av. Atahualpa) ferry passengers every day through sleepy Andean scenery from Cajamarca to Celendin, though Movil Tours is the only one I found that goes straight through to Chachapoyas.
Celendín is a quiet town of about 15,000 people with plenty of restaurants and basic hotels within a few blocks of the Plaza de Armas. Combis leave from the city center to the quiet villages nestled in the hills above, and for a few soles one can enjoy a lovely view and a stroll through traditional rural Andean life. There is no organized tourism in the area, but travelers with time and a penchant for exploration can arrange transportation to a stone forest (bosque de piedras), waterfalls, and pre-Inca ruins.
Several bus companies leave Celendín for Leymebamba, generally around midmorning. The road between the two towns is just 144 kilometers, but the hairpin curves, stunning views, and drastic climate changes will truly make you reach for your thesaurus (and your Dramamine).
From Celendín the bus winds up through lovely Andean farm scenery to a pass of 3100 meters before plunging into the Marañón River valley to cross the river at 975 meters. The descent is through a practically untouched desert wilderness of cactus, palo verde, spidery agave, and flowering shrubs. As the bus honks its way around every blind corner the Marañón River comes more and more into view, a flat gray ribbon woven through a narrow swath of green.
When the bus finally reaches the Marañón and the tiny improbable town of Chacanto on its banks, passengers throw off their jackets and the bus driver pops open the rooftop ventilation to counter the sudden jungle heat. The road follows the river for only a dozen shady kilometers before beginning its torturous climb back up into the arid mountains.
After many more hours of desert the bus begins to encounter signs that warn of "Area de Neblina" (fog). Black Mud Pass (Abra del Barro Negro--3700 meters) is a 180 degree change from the arid scenery that has come before. Roof tiles are black from the moist climate, and lichens and ferns sprout from the stone walls. Animals graze placidly in emerald pastures beside potato fields.

The area around Leymebamba (2200 meters) is especially interesting for those who want to explore the pre-Inca culture of the Chachapoyas people. In 1996 a group of farmers discovered a group of chullpas (mausoleums) by the Laguna de los Condores, with more than 200 mummies entombed inside. These are now being studied in the Museo Leymebamba, which is located a few kilometers outside of town.
The hike out to Laguna de los Condores requires a minimum of three days. If you have time, other less famous but equally interesting sites such as Chuquibamba, the burial sites of La Petaca and Diablo Huasi, and the valley of Atuen can be accessed through another three- to four-day hike.
Though there are no tour agencies in Leymebamba, ask at the hotels La Casona de Leymebamba, or Laguna de Los Condores, or the Museo Leymebamba, to be connected with a guide.
From Leymebamba the road follows the Utcubamba River through a fertile valley full of sugar cane, banana plantations, balsa trees, and a dozen colorful varieties of bromeliads that grow on anything which stays still long enough. The mountains around this area are full of ruins of the Chachapoyas people, including the spectacular fortress of Kuelap, the mausoleums of Revash, and the sarcophagi of Karajia; the easiest way to visit these sites is to go to Chachapoyas and hire a guide, but there is also lodging in the small towns of Tingo and Maria (closest to Kuelap). Though public transportation in the area is sparse, locals are always willing to help out a stranded traveler if they have room.
The guide books remain right about the best time to visit being during dry season as roads may become impassable during heavy rains. Your best bet is to check ahead by calling tour agencies in Chachapoyas, but don't let anything deter you from having an amazing adventure.