NUEVA COLOMBIA, Colombia -- Antonio unscrewed a vitamin bottle and dumped a few chunks of coca base, a precursor to cocaine, in his hand. In this part of central Colombia, along the Guayabero River, mercancía is as good as cash. A gram is worth 2,000 pesos and might buy you a Coca-Cola.

Colombia has made dramatic progress in shaking off its dark past of drugs and guns. Coca crops and the homicide rate have dropped dramatically over the last decade, and the nation’s guerrillas have seen their ranks decimated by military operations and defections. President Juan Manuel Santos has hailed this new Colombia as an investor hotbed and magnet for tourism.

But in Nueva Colombia and other villages along the Guayabero River — where government presence is so tenuous that coca passes for currency — it’s clear that the nation’s transformation is incomplete.

“The only time we see the government is when they are either shooting at us or fumigating our coca crops,” said Pablo Vargas, 55, a cattle rancher who also grows coca shrubs. “They’ve never offered us loans, or set up a buying center or built a road that might let us switch to other crops.”

Last week, the United Nations reported that Colombia’s coca crops were on the rise for the first time in five years, albeit slightly. But in the Guayabero region, production was up 13 percent from 2010 to 2011.

The region has been a stronghold of the Revolutionary Armed Forces of Colombia, or FARC, since the 1960s and their presence in the area is palpable. Banners promoting the FARC’s 7th Front hang across streets and recruitment signs are stenciled on walls. On a recent trip down the river, FARC patrols were spotted twice while government troops were nowhere to be seen.

The region lives under two sets of rules, said Jessie Pereira, a farmer in the community of La Carpa: state law and guerrilla law, or what locals call the law of the jungle.

Cooperating with the military is a punishable offense, he said. And while the FARC don’t dictate what farmers grow, those who do grow coca need guerrilla permission to sell it outside the region, he said.

“We live in their territory and have to obey their regulations,” he said. “If you break their laws then you’re against them. And if you’re against them, well, there are consequences.”

While the FARC’s presence has made many of the villages off limits to civil servants and engineers who might bring in basic services, the communities’ sense of government neglect only feeds discontent and the FARC’s ranks.

Most of the towns only have electricity a few hours a day and don’t have treated water. While health centers exist, they rarely have doctors.

In the hamlet of Puerto Nuevo, Luz Miriam Garzón, 38, stood outside a roofless cinderblock church that was being used as a vulture roost. She said the road into town is so bad that priests only visit once or twice a year, so the community lost interest in finishing the structure.

“I don’t know if it was God who forgot about us or the government,” she said, “but we’ve been abandoned.”

The government acknowledges the problem. With U.S. funding, authorities launched a pilot project in 2007 to push public services into these long-neglected communities in lockstep with the military.