Complex sentence: According to the ancient tradition and regulations laid down by Charles the Fourth in the 14th century, the jewels are exhibited only to mark special occasions, the last time was in 2008 on the occasion of 90th anniversary formation of Czechoslovakia.
Split into simpler sentences: According to the ancient tradition and regulations laid down by Charles the Fourth in the 14th century, the Jewels are exhibited only to mark special occasion. The most recent showing was in 2008, on the occasion of 90th anniversary formation of Czechoslovakia.