Essay about GRE Arguments practice

I am prepared for GRE, and I choose one topic from GRE Arguments topic, hope someone could give me some feedback about the points I made and if there is anything I could work on to improve my GRE arguments essay. Many thanks!

The topic I choose is:
Woven baskets characterized by a particular distinctive pattern have previously been found only in the immediate vicinity of the prehistoric village of Palea and therefore were believed to have been made only by the Palean people. Recently, however, archaeologists discovered such a “Palean” basket in Lithos, an ancient village across the Brim River from Palea. The Brim River is very deep and broad, and so the ancient Paleans could have crossed it only by boat, and no Palean boats have been found. Thus it follows that the so-called Palean baskets were not uniquely Palean.

Write a response in which you discuss what specific evidence is needed to evaluate the argument and explain how the evidence would weaken or strengthen the argument.

My essay is:
While it may be true that the Palean baskets may not only be made by the Palean people, this author’s argument does not make a cogent case. It is easy to understand why people would assume that the woven basket is not unique for Palean, but this argument is rife with holes and assumptions, and thus, not strong enough to lead to this conclusion.

Judging by how deep and broad the river is, the author asserts that the residents can only cross the river by boat. It is not clear, however, boats are the only way for citizens to cross the river by. For example, ancient Egyptian could build the colossal Pyramids without crane but with the mysterious method we have not even figured it out till now. Ancient people can come up with inconceivable ways to cross the river, too. Unless the survey is fully representative, it cannot be used effectively back to the author’s argument.

Additionally, the author implies that the baskets could be made by other tribes, despite its distinctive pattern, because they find no boats around. While no boat could indicate no one crosses the river. The article does not give us a lucid historical background to support there are indeed no boats a long time ago there. Though there is no boat to be found, we do not know if the archaeologists miss somewhere nearby or the boats were too fragile to remain intact. Some boats may leave nothing but debris, which could barely be found by people. To strengthen his/her argument, the author should prove there are no boats in the very beginning.

Building upon the implication that there is no boat in Palea, the author suggests that woven baskets would from a different region other than Palea. If the river has been deep and board since the very beginning, this may be true. But if a long time ago Palea is connected with Lithos, this may not be true. As the weather changed dramatically since the glacier era, it could be no river before. Consequently, whether there are boats or not may have no impact on the origin of woven baskets. Regardless of whether there is no river or not, the author does not effectively show a connection between the boats and the baskets.

Examine all the various angles and factors involves, the argument does not justify ruling out the Palea as the only place produced the woven baskets. While the evidence does highlight a possibility, more information is required to warrant the assumption.