JAKARTA, Indonesia — In the past 12 years, the annual Ubud Writers and Readers Festival on the Indonesian resort island of Bali has earned praise for its provocative panel discussions, book introductions and film screenings.

But during this year’s five-day gathering, which ended last Sunday, it was what the international festival did not present that caused the biggest stir.

Just days before the gathering opened to the first of nearly 30,000 visitors, the local authorities in the Balinese town of Ubud ordered its organizers to cancel eight events related to the bloodiest period in modern Indonesian history: the killings of an estimated 500,000 or more people during state-sponsored purges of suspected Communists and their sympathizers in 1965-66.

The authorities’ directive was part of a widespread pattern. Although the 50th anniversary of the trigger for those killings passed last month with little notice aside from a few news stories, officials have lately begun cracking down on any exploration, analysis or remembrance of the purges.