Present a threat to mainstream media, largely because they

Blogs; are cheap to produce.

Explanation:

Blogs are a dangerous alternative to mainstream media. In a blog, the author performs many of the same actions that a large team at a media company produce, such as researching, writing, recording, editing, publishing, advertising, etc. Moreover, blogs are usually very cheap to produce, and as they require very little investment, can often be very profitable.

first, the romans stayed isolated because they had to defend their own territories from neighboring cities that were harassing them, like the etruscans. second, once the romans managed to defeat their neighbors, and started to expand their territory, they started to build roads and bridges. finally, now that the romans have covered their territory with roads functioning as highways, they could mobilize their legions faster to assemble larger military units in a specific place

the aksumite empire was an ancient kingdom located in what is now northern ethiopia from the period of 100 ad to 940 ad. its capital was the city of aksum. the kingdom established itself as one of the 4 great powers at its time, along with persia, rome, and china.

the kingdom was rich in goods like gold, iron, and salt. it established strong commercial ties with the regions governed by rome, egypt, and persia (arabia). aksum was a key location in this commercial network. trade was also facilitated with the introduction of the aksumite currency.