It's a Russian solstice celebration..................................... .............................. wild guess You do not celebrate this ?
summer Christmas party like a (spring harvest?)harvest party in farming when all the crops have been harvested and processed and you then have some spare time to relax with lots of food and supply's and social gatherings would take place after a long cold winter and working really hard to get the crops in and processed. traditionally this is the times when marriages were arranged, people would be introduced to relatives and see new born babys, trade special items and share medicines etc...