Conversation so far:
what is the importance of ramadan in Islam
Ramadan is the most sacred month of the year in Islamic culture.
when was Ramadan established
Ramadan was established in the 7th century when the Quran was revealed to the Prophet Muhammad. His revelation began in 610 CE in Mecca at Hira Cave on Mount Nur.
when is Ramadan scheduled for in 2020
Ramadan for the year 2020 starts on the evening of Thursday, April 23rd lasting 30 days and ending at sundown on Saturday, May 23.

Question: when did the celebration happen in 2019
Self-contained rewrite: when did Ramadan begin and end in 2019