During pax mongolica, why were traders and travelers treated as they were?

as intruders in the land, they were escorted out quickly to keep the peace.
as deliverers of both news and goods not produced in the region, they were seen as important to the economy of the region.
they were typically robbed and left to the elements.
there were only a few cases of successful trade transactions during pax mongolica.

The political cartoon below was drawn by thomas nast in 1871: a political cartoon shows a heavy set man with a long nose and a beard in a suit and vest. he is smoking a cigar and has a menacing expression. he leans against a large box that says, in counting there is strength. on top of that box is a smaller container labeled, the ballot. dialogue under the cartoon reads, thats whats the matter. boss tweed, as long as i count the votes, what are you going to do about it? say? public domain what issue does this cartoon address?