setting

So, you're hitting the road again?

The story told in Golden Sun takes place on an imaginary world called Weyard. As the times you plan in, Weyard is not fully known and, as the in-game map says, only two continents are explored: Angara, which is the continent of most of the protagonists' journey and probably the most populated, and Gondowan. The reasons why other lands are not explored are mainly geographical: both Angara and Gondowan are, on the East coasts, surrounded by the Great Eastern Sea, and only very rich men have the chance to get a ship and sail across seas. Then, Angara is surrounded by sea even on North, and got a high mountain range and an unknown continent on the West, and both will be affected by the events occuring during Golden Sun. Gondowan has a mountain range on the South and the same unknown continent on the West. Angara and Gondowan are united by land and there are only two ways to travel from the two: by land, traveling on a road called The Silk Road, established by a famous merchant who buys silk in Xian and sells it in Tolbi, or by sea, on a ship crossing the Karagol Sea.   
Most of the inhabitants of Weyard are normal people with their culture and traditions (Weyard resembles the Earth itself, with Oriental people and Arab-like societies) which live a normal life. But there are stories, thought myth and legends, of ancient societies and populations, who grew thriving with the help of Alchemy: as official Golden Sun story said,

Alchemy wrought the base
elements of humanity
into thriving civilizations,
like lead into gold.

But, during the centuries, the power led men to dream endless riches, eternal life, dominion over the world, and started to rage wars. Before the world could fall in wars and death, a group of wise and brave men sealed the power of Alchemy deep in Sol Sanctum, a temple in Mounth Aleph, overseen by the town of Vale, lying at the foot of the mountain. So, year after year, the power of Alchemy started to fade, and became myth.
However, Alchemy did not completely fade. The town of Vale itself, had a big Psynergy stone, which influenced a lot its people. Psynergy is a form of psychic power, fueled by Alchemy and based on the four elements which make all matter, Earth, Fire, Wind and Water, which is led by the spiritual power of the mind. So, under the influence of that stone, every person living in Vale, is an Adept, that is a person who can use the powers of Psynergy. Being Earth and Fire adepts, the people of Vale became a close-knit community, who to protect Psynergy from diffusion and evil reasons, were not allowed to give confidence to strangers and enter and leave the town as they wanted.