The names of the gods asked for in the last question are Perun and Veles. Perun was the Slavic god of thunder, also god of warriors and peasants. He was conected with the hawk and the oak. Veles was the god of cattle, magic, pastoralists, and the underworld. Veles would steal Perun's cattle or Perun's wife, causing drought, after which Perun would scour the entire land searching for Veles. Veles would change forms, but once Perun found him, he would strike him with his axe (the source of thunder bolts), made of stone or gold, and Veles would burst into rain, bringing life to the land. Later on, Veles would reincarnate in the underworld and plot revenge on Perun.
Once Veles kidnapped Perun's son, Yarilo, the god of spring, and raised him in the underworld. But Perun discovered this and forced Veles to let Yarilo spend half a year in the upper world. The time when Yarilo is in the upper world is known as spring and summer, while during the winter he has to spend time with Veles in the underworld. During this time the upper world would be ruled by Morana, Yarilo's sister and Perun's daughter, the goddess of winter.
These two gods were mentioned in a treaty the Byzantines made with Russians. The Russian envoys raised their weapons and summoned these two gods to be their witnesses. Later on under Vladimir the Great the Russians offficially converted to Orthodox Christianity, although the old faith persisted at least until the 15th century. Aside from Russia, Ukraine and Belarus, signs of worship of these gods can be found in Slovenia, Croatia, Serbia, Macedonia and Bulgaria.
OK, so let me ask a new question. Priests of which Germanic god determined whether to go to war or not by observing the behaviour of a stallion walking over a row of spears? I think Tacitus mentioned this tradition. This tradition was also taken over by Abodrites, a Slavic tribe that lived in northeastern Germany.
