I can't recommend Gazetteer V enough if you're going to play a Tepestani!
It's got all sorts of great info: customs, common phrases, beliefs about the world, naming conventions, etc.
One of the most interesting beliefs is how they categorize the beings of the world, according to the seasons.
Spring's Children are the fey, the oldest living creatures, also immortal. As they cannot die, they have no respect or understanding of death. Spring's Children were created by the gods
Daghda (goddess of fertility and the forest),
Diancecht (god of healing), and
Lugh (god of magic and secrets). The Tepestani also lump in any demihuman with a longer lifespan than humans (elves, dwarves, halflings, and gnomes) as the fey.
Summer's Children are humans and natural animals. The gods felt that giving the fey immortality was a mistake, and therefore created Summer's Children with a limited lifespan--since they experience all facets of life and death and thus respect life wheras Spring's Children do not.
Belenus (god of the sun) is credited with creating humans while his wife
Brigantia (goddess of nature, industry, and agriculture) and her brother
Mannanan mac Lir (god of of water and aquatic creatures) created the animals.
Autumn's Children are monsters: goblins, hobgoblins, trolls, kobolds, ogres, hags, lycanthropes, dragons, and most monstrous humanoids, magical beasts and aberrations.
Arawn (god of the dead) and
Morrigan (goddess of discord and war) created Autumn's children out of jealousy. They felt they could improve upon Summer's Chilldren but failed miserably, creating misshapen mockeries of humans and animals.
Winter's Children are wholly unnatural: elementals and the undead. They are the creation of
Math Mathonwy (god of dark magic and secrets), who is believed to have created them to spite the other gods since they ignored him when creating the other children. Supposedly Math Mathonwy based Winter's Children on the fey, but his cold and evil nature tainted his creations so that they were eternal but utterly devoid of life.