The Old English word for holiday is haligdæg, meaning “holy day,” or “religious anniversary”—a solemn designation.

Over time, the word began to cover religious festivals, finally coming to cover most any day of exemption from labor.

Today, we use the word even more liberally, applying it to everything from “Boss’s Day,” on October 16th, to “National Hairball Awareness Day” on April 29th.

With the huge number of holidays, great, small, and weird, there are bound to be a few esoteric holidays that are overlooked, even amongst religious holy days. This is true even for the world’s major religions.

All holidays tell a story of some kind. These narratives can be epic in scope, or small and personal, but all are fascinating windows into the cultures which spawned them.

So why miss out on the smaller parts of the human story? Together, let’s explore these 6 religious holidays you’ve never heard about.

Paganism: Yggdrasil Day

In Norse Mythology, Yggdrasil is the enormous tree of life, an eternally green ash of cosmic proportions. It is carried by three roots, the first of which resides in Asgard, home of the gods. The next root lies in Jotunheim, the land of giants. The third and final root plunges into Nifheim, the origin of cold rivers.

Its branches tie together the nine worlds of Norse mythic cosmology, binding together the fabric of the universe, moving through lands inhabited by humans, gods, and giants, joining them all together. It is a living bridge.

The symbolism is unmistakable—a major part of the mythical Yggdrasil is the representation of the living connection between all things.

Yggdrasil Day is a fairly new holiday in the Neopagan tradition, falling on the 22nd of April, and celebrates this connection by honoring what Yggdrasil represents. This day is a time to contemplate the place of humankind within the nine worlds, and to celebrate the blessings of nature, often shown by planting a tree. This is also a time to celebrate one’s culture, heritage, and spirituality.

Regardless of faith, Yggdrasil Day is a great opportunity for anyone to give back to nature and recognize our interdependency on both one another and the natural world.

Christianity: Pentecost

Few Christian holidays are truly unknown, but Pentecost is, perhaps, the least talked about.

This holiday celebrates the time when the Holy Spirit descended upon the apostles and other followers of Jesus Christ 10 days after Jesus’ ascent to heaven, as described in Acts 2:1-31.

According to these verses, the descent of the Holy Spirit occurred while about 120 followers of Christ, including the Apostles, were celebrating the Jewish day of Shavuot. The group was suddenly assailed by the sound of a “rushing mighty wind,” and there appeared bursts of fire which hovered over each individual. They were filled with the Holy Spirit, and began to speak in one another’s languages.

Today, this miraculous event is not widely celebrated, often being overshadowed by Mother’s Day, but is still quite religiously significant. The holiday is most commonly recognized by liturgical churches, and can be celebrated through special worship services and the wearing of red, which symbolizes the fire that came down on the followers of Christ. Many churches also hold baptisms and confirmations on this holiday.

Ultimately Pentecost is the celebration of the Holy Spirit, and its ability to unite and dwell within individual Christians.

Islam: Laylat al-Qadr

This holiday, translated as “Night of Decree,” or “Night of Destiny,” is the celebration of the revelation of the first verses of the Quran to the Islamic prophet Muhammad.

It falls on one of the odd nights of the last ten days of Ramadan, and on this night it is believed that the blessings and mercy of Allah are most abundant, that sin is forgiven, and that prayers are accepted. It is also, on this holiday, that Muslims believe that the annual decree is accepted—the moment when God sends down His decrees from heaven to earth, wherein He destines the actions of creation for the next year.

Muslims offer extra prayers during this time, and hold a vigil, seeking Allah’s forgiveness and mercy. Most of all, they take this time to deeply read the Quran. By devoting this time to remember Allah and study His word, Muslims hope to receive the blessings connected to the holiday.

Buddhism: Buddha’s Birthday

To much of the Western world, Buddha’s birthday is largely unknown, but in the Buddhist tradition, this is a very important day.