This is telecommunications medium, which became popular in the mid-1900s, sends audio and video, usually into individual homes.

The correct answer is television.  

Even though we can trace mechanical television back to the 1800s, by 1934 every television had been converted into the electronic system. By 1938 television sets were produced and released commercially.  Since the 1950s television has become a crucial form of communication found in every house.

it affected it because the kingdoms (with trade) slowly got richer and richer.