How did early trade lead to specialization?

Early trade lead to specialization because Artisans worked with one set of resources and traded their products for something someone else worked well with.

Let's say that the artisan had several form of arts but he realize that most market's interest that he got came from oil-based painting.

This artisan then eventually will realize that focusing all of his time solely for his oil-based painting will be the best for his economic interest.