Snowpeak

Snowpeak is location in Twilight Princess. It is a mountainous region that composes all of the Peak Province, situated in the northwest portion of the Hyrule map. Snowpeak is home to the fifth dungeon of the game, Snowpeak Ruins, and it is mainly inhabited by Ice Keese and White Wolfos, along with two Yetis, Yeto and Yeta. The only entry to Snowpeak, other than warping, is through a small tunnel in Zora's Domain, located in the Lanayru Province. The highest point in Snowpeak is Snowpeak Top, wherein lies a tree with frozen leaves that helps Link race down the hill to Snowpeak Ruins.

History
After learning from the Sages that one of the shards of the Mirror of Twilight is located in Snowpeak, Link and Midna head off to the area to try and find some clues. However, the pair encounter Ashei near the entrance to Snowpeak, who tells them that a beast has been frequently seen in Zora's Domain stealing a rare fish known as the Reekfish, found only in the Zoras' home. Hoping that Link will found out more clues about the Snowpeak creature, Ashei hands over a sketch of the "beast" to Link. The young hero then heads off to the Kakariko Graveyard and shows Prince Ralis Ashei's sketch, who immediately recognizes the creature as well as the Reekfish depicted in the drawing. The prince thus provides Link with the Coral Earring, which is a special lure necessary to catch the rare fish.

Catching a Reekfish allows Link to use his wolf olfactory senses to pick up the fish's smell, whose stench eventually leads him to Snowpeak Top where Yeto, the so-called Snowpeak beast, is found. Link tells Yeto of that he is searching for a fragment of the Mirror of Twilight, which prompts the Yeti to invite him to his mansion located at the bottom of Snowpeak, saying that he found a mirror piece earlier on. After snowboarding down the mountain using the frozen leaves of a nearby tree, Link enters the Snowpeak Ruins and ultimately recovers one of the Mirror Shards upon the defeat of Blizzeta.

From this point on, Link will be able to find Yeto and Yeta at Snowpeak Top, where they will offer to race the young hero down the mountain and reward him with a Piece of Heart if he bests both Yeti.

Theoretical Connection & Explanation
The Snowpeak Mountains are not present in Ocarina of Time, but are in its successor, Twilight Princess. If viewed from the Gamecube version of Twilight Princess's layout of Hyrule (that which is the most accurate in relation to Ocarina of Time's geographical layout), they would be northwest of Hyrule Castle, beyond the Gerudo Desert. This was a completely unexplored and undeveloped region in Ocarina of Time, but has now been further explored both by the developers and by the citizens of Hyrule. Snowpeak probably existed at the time of Ocarina of Time, but had not been explored and settled, and from the information gathered from Twilight Princess, it never really was settled -- except for the mansion, which had been abandoned and left to freeze over and ruin.

It is obvious that Yeto and Yeta did not build it, but have rather adopted it as their home -- so what are the origins of the Snowpeak Ruins? Perhaps a convoy of Hyrule's exploration team were sent to explore this uncharted region of Hyrule and to establish a base of operations. This theory is backed up only by the mass amount of suits of armor, weapons, and cannons present in the ruins. This was more than a mansion, it was a fort for an army, and judging by the elegance of the fort, it had to have been Hyrulean. The suits of armor even match those found in Hyrule Castle.

Trivia

 * Snowpeak is the third snow location in The Legend of Zelda series, the first being Snowhead from Majora's Mask, as well as Frozen Hyrule from Four Swords Adventures.
 * Interestingly, the Spanish name for Snowpeak is "Pico Nevado," which is the same name as Snowhead from Majora's Mask.
 * This is one of the two only regions in the game without Golden Bugs. The other is Ordona Province.