In the statement the author believe woven baskets are not only uniquely made by Palean people because a "Palean" basket is founded in Lithos and it was impossible for Palean to cross the Brim river to the neighboring country. The evidence from the argument seems plausible at first glance, yet further explanations and proofs are wanted to make the argument more comprehensive and convincing.
For starters, there is a "Palean" basket found in Lithos, and thus the author assumes it is definitely made from Lithos citizens. However, only one basket found in such area is not substantiated enough to verify Lithos people can also produce baskets. Maybe this basket was a counterfeit from a certain scholar who hates the Palean culture. Or maybe the basket was carried by the following citizens who was originated from Palean. Only if the arguer is able to provide a certain number of Palean baskets found in Lithos will he claim citizens in Lithos can also make the baskets.
Moreover, the author maintains that there is not any boats discovered near Brim river, so Palea people have no way to cross the river to Lithos. Nevertheless, Palean civilization is a prehistoric culture, which means a lot of facilities at the moment might be destroyed. Even if archaeologists do not discover any of boats, it does not follow those boats did not exist. Maybe boats were or maybe there was a tremendous natural disaster such as flood, which made all boats of Palea sunk in the bottom of the ocean. Even if there is no any boat built back that time, people might still try other ways to commerce with people in Lithos. For example, people might detour from other mountains and pass through a part of Brim river that was shallow and easy for people to swim through.
What's more, the author seems to believe the basket found in Lithos uses the exact the same skill as ones made by Palean. However, maybe the basket was made by simple craft which was ubiquitous at that time. Even if the author has proved that the basket found in Lithos was made exactly the same skill as what Palean people did, there are still some suspicious points that need to be clarified. If Lithos people can also make this kind of woven basket, they must share the similar textures, craft and tools. Yet the author fails to mentions this part in the argument. Unless the author can also provide with those identical ingredients and tools found in Lithos, he cannot contend Lithos people were also specialized in making wolen baskets.
To conclude, the author should provide more evidence to make his point more solid.