Brazilian officials who keep tabs on the region's so-called "uncontacted" inhabitants from afar fear that the tribe was forced to flee the area as a result of the apparent interaction, or may have even been wiped out by the suspected drug dealers.

The worries began late last week after a government-run guard post in the area was attacked by a group of armed men believed to have been smuggling drugs between Peru and Brazil, the BBC reports.

Since the attack, officials have found no sign of the tribe, which was first photographed from the air three years ago. Carlos Lisboa Travassos, the head of Brazil’s Isolated Indians Department, told local media that the guards found a broken arrowhead in one of the attacker’s backpacks that was left behind, suggesting the armed men had made contact with the tribe.

“Arrows are like the identity card of uncontacted Indians,” Travassos said. “This situation could be one of the biggest blows we have ever seen in the protection of uncontacted Indians in recent decades.”

Authorities also found a package containing 44 pounds of cocaine in the area, LiveScience reports, further adding to fears that smugglers may have wanted to remove the tribe from the region in order to clear the way for illegal drug running.

The area where the tribe lives, the Javari Valley of the western Amazon, is one of the most isolated regions of the Amazon and has the highest concentration of known isolated tribes. Brazilian officials keep an eye on the tribal lands but avoid contact with the inhabitants in order to avoid exposing them to germs from which they have no immunity.

At least eight similarly isolated tribes have been spotted in the same region, making the possibility of drug trafficking in the area that much more of a worry for officials hoping to protect the indigenous way of life.

LiveScience has photos of the missing tribe here.