Why is the article the map that shows that the city vs. country is not our political fault line a secondary source?

Explanation:

FREEPORT, Maine — Contrary to conventional wisdom, the most significant and abiding divide in American politics isn’t between city and countryside, but rather among regional cultures. Rural and urban places certainly have distinct interests and priorities, but in our awkward federation their differences have taken a back seat to the broader struggle between our constituent regions.

Sectionalism isn’t, and never has been, as simple as North versus South or an effete and domineering East against a rugged, freedom-minded West. Rather, our true regional fissures can be traced back to the contrasting ideals of the distinct European colonial cultures that first took root on the eastern and southern rims of what is now the United States, and then spread across much of the continent in mutually exclusive settlement bands, laying down the institutions, symbols and cultural norms later arrivals would encounter and, by and large, assimilate into.

Understanding this is essential to comprehending our political reality or developing strategies to change it — especially as we approach a momentously consequential midterm election.

the first historical instance of china engaging in internationalism was during the han dynasty.[1] at the start of the han dynasty, the huns in the north were attacking the frontiers of han and trying to obtain riches. emperor wu of han wanted to gain an alliance with a country called dayuezhi so the two countries could join together and fight against the huns.[2] to obtain this alliance, emperor wu sent zhang qian to the west to establish economic and cultural connections.[2] history records that during the han dynasty there were four primary avenues of contact between china and europe. they included the northern land route, the central land route, the southern sea route, and the far southern sea route.[1] the most famous of these routes is the central land route, or the classical silk road, comprising a network of roads stretching from northwest china to the ports of syria and the black sea, which passed through the oasis of the turkestans and northern persia.[1] the silk road was significant for chinese emperors because it provided dominance over central asia by developing resources and provided new markets for the export of china's most valuable resources.[1]

the enslaved people onboard suffered from illness with some frequency