Celebrating the dead, whether we call it Halloween, All Hallows Eve, Dia de los Muertos, All Souls Day the world celebrates for three days: October 31 through November 2nd.
When the Buddha spoke about one of the great sufferings, he spoke of death. Death was inevitable and living in fear (suffering) was a waste of time.
Ancient history tells us that celebrations to commemorate death have been around since organized human groups have existed. As societies became more sophisticated, the mourning celebrations became more intricate.
Society has adapted the meaning of the celebration to suit its relationship with death. In the US people tend celebrate Halloween in a child-like manner with costumes and spooks. Whilst in Mexico many people still go to the cemetery with offerings of food and flowers for the departed. In Europe, ancestor veneration has been a common practice, lighting candles to illuminate the way and baking soul cakes is still traditional. In China you have the Ghost Festival and Japan has the Bon Festival.
All these celebrations are proof that we are more connected with each other than we recognize. Explaining our mortality and celebrating the lives of our ancestors is universal.