Final answer:
Bankside was historically London's entertainment district due to its concentrated array of theaters and entertainment venues, situated outside the city limits to legally host performances.
Step-by-step explanation:
Bankside was considered the entertainment district in historical London primarily because it had a high concentration of theaters and entertainment venues. The area was located outside the city limits on the left side of the River Thames, where theatrical activities could take place as they were illegal within the city itself at that time.
The vicinity of these theatres to pubs and their connections with dining and drinking establishments made them lively centers of entertainment. This atmosphere created a hub where people could enjoy plays—with notable repetition to ensure audiences caught the essentials despite distractions—as well as other forms of popular culture and entertainment prevalent during the industrial age.