Sivan 19 is a historic Jewish fast day that commemorates a massacre that occurred in Blois, France, in 1171, marking the first blood libel in continental Europe. It also represents other anti-Jewish violence during the Crusades era, such as the Rhineland massacres. Sivan 19 corresponds to June 4.

Sivan 20 commemorates the massacre of Jews in Blois, France, in 1171, where many were burned alive due to false accusations of blood libel. This day was established as a fast day to remember this and other tragedies faced by the Jewish people. Sivan 20 corresponds to June 5.

Sivan 21 is significant in Jewish tradition as it is the date of the holiday of Shavuot, which commemorates the giving of the Torah to the Israelites at Mount Sinai. In 2026, Sivan 21 corresponds to June 6.