It's ancient vs. modern in this matchup. First lets take a look at the Yanomamo weapons. (Sorry if this seems rushed. I'm short on time.)
They are a South American jungle tribe still in existance today, on had basically all of their weapons drenced in poison. Their special weapon was a blowgun. The dart uses the most deadly animal toxin ever known-poison dart frog venom. Coated with poison, these weapons were stealthy, accurate, and could bring a large animal down with its poison. (It is important to know that the poison was boiled to make it super potent).
For lange range, they had a bow and arrow that Dr. Dorian would love. According to http://yanomamo-clarencema.blogspot.com/, "The point has one-inch intervals where they are rather purposely weakened, giving the arrows the ability to break off into the body of the victim, enabling the poison to be absorbed and making it extremely difficult to remove."
For mid-range, the Yanomamo had a poison tipped spear. All of the poison may really be the deciding factor in this matchup.
Their short range weapon looks like an arrowhead, but that would be crazy if it were.
It looks like one of those kitchen prongs, only as a dagger, and a tool of war at that.
Then there are the Thracians, which are millenia behind, but may be more technologically advanced. These Greek soldiers had their fair share of wins ove the course of history. Whereas the Yanamomo had no armor, these soldiers carried a shield called a pelte, and sometimes wore a helmet. However, this was the only armor they could get.
Their long range weapon was a sling. Hopefully you won't need a picture. Next came their short range weapon; a sword called the rhomphaia.
Their long range weapon was a javelin, of which they carried several. Finally, they had their special weapon, as sword called the falx. The design was so great, that the Romans later took it under their wing.
The battle boils down to whether the arrows/spear can penetrate the shield or not. That will ultimately decide the winner.
Analysis: At first I didn’t believe it myself, but a spear is definitely going to go through an ox hide shield. That and the Thracian wasn’t as well armoured as he may have seemed. On the plus side, the Yanomamo’s poison was potent enough to possibly kill hundreds of humans with one arrow. All of that venom will add up fast, and if the Thracian is struck with any poison of that calibre, he doesn’t stand a chance.
The Thracian looks around in the fields, wondering if something is waiting for him in the forest that is only about twenty metres away. His keen eyes glance, but pick up nothing. A bush rustles. It was probably just an animal, but just for safety’s sake, he kept his shield up, and was hunched to the floor.
Meanwhile, in the jungle, the Yanomamo thinks that the Thracian spotted him, so he moves into a bush and draws his poison arrow. He then lets it fly through the distance. It was just as well that the Thracian kept his shield up, for an arrow had struck it. He removed it and threw it to the floor, but another arrow flew and landed on his helmet. The Thracian plucked it out and pulled out his sling, grabbing a large rock from the ground. He got a steady momentum going, and then unleashed the projectile, which was aimed at the bush in which his enemy hid. It flew through the air quickly, but the Yanomamo saw it coming and had enough time to duck out of the way. The Thracian let loose another volley of rocks for a while, but he was too far away for them to be effective.
Then, surprising him, the Yanomamo jumped out of the bush and threw a spear at his target. It actually hit the Thracian's shield and went through, but didn’t hit the target, who dropped his pelte and the enemy spear embedded in it to the ground. The Thracian, not to be beaten at his own game, drew back one of his javelins and let it fly. Though thrown at mid range and flying through the air fairly quickly, the javelin hit a tree.
The Amazonian warrior then ducked behind a hollow log. The Thracian was now in the jungle, ready to take on his opponent if he could only find him. A blowgun dart grazed the back of his foot. Falx drawn, he notices that the shot came from the hollow log. He swings the curved sword down at the stump at full force, cracking it in half, only to look up and find his enemy a couple of metres away. He was quick.
The Yanomamo lets another dart loose, but as he is running and not particularly aiming, his shot misses. He then scurries up a tree. The Thracian exhausts all of his javelins just trying to get the Yanomamo. However, his final javelin comes so close that it scares the Yanomamo into jumping down. While he is down, the Thracian goes for another falx swing, but unfortunately, the jungle warrior rolls away, though he is still a bit slashed. The Thracian then pulls out his rhomphaia and makes a stab at the opponent. He gets a couple of small shots, though the Yanomamo is proficiently jumping away. The Yanomamo then draws his dagger and stabs his opponent several times. The Thracian then goes for a might downward blow at the South American with his rhomphaia, only to see the Yanomamo release his bowstring and send an arrow through his heart. The Yanomamo then kicks the dazed opponent down, and raises his bow and cries out.