Below is an article published by Oromocentre;

Irreechaa is a national Thanksgiving Day celebration that repeats once or twice in a year and involves special activities or amusements. The 2012 Irreechaa Birraa festival is one of the main celebration in every year at the beginning of Birraa (the sunny new season after the dark, rainy winter season) throughout Oromia and around the world where Diaspora Oromos live on the theme of “Moving Forward: Restoring the Spirit of Oromummaa”.

The Oromo celebrates Irreechaa to thank Waaqaa for the blessings and mercies they have received throughout the past year at the sacred grounds of Hora Harsadi (Lake Harsadi), Bishoftu, Oromia. They celebrate Irreechaa not only to thank Waaqaa (God) also to welcome the new season of plentiful harvests after the dark and rainy winter season associated with nature and creature.

On Irreechaa festivals, friends, family, and relatives gather together and celebrate with joy and happiness. Irreechaa Festivals bring people closer to each other and make social bonds by following their tradition and religion. For almost 6400 years, Oromo families have gathered to take part in the largest Thanks-giving ceremony of the ‘Gadaa’ calendar. Friends, old and new, parents and children join together in a celebration on the goal of ‘Walooma Uumaa-Uumamaa’ (Creator-creatures Harmony).