In almost every fantasy world Dwarfs are almost always shown to have superior technology compared to other races. Why is that?
In mythology, dwarves have been portrayed as master smiths, making the most amazing items in their forges.
In Norse mythology, the dwarves Sindre and Brokk forged Thor's hammer Mjölnir, Odin's ring Draupnir, which drips eight new gold rings every ninth night, and the boar Gyllinbursti, whose golden bristles glowed in the dark. Their rivals, the Sons of Ivaldi, forged Sif's magical golden, growing hair (after Loki in mischief cut off her original hair), Odin's spear Gungnir, and Frey's ship Skíðblaðnir, which can be folded up and put in a pocket.
In Der Ring des Nibelungen, which is based on the Germanic Nibelungenlied and the Nordic Völsunga Saga and The Eddas, Alberich the Dwarf forges the Ring, while his brother Mime forges the Tarnhelm (which can turn the bearer invisible). The Ring is based on the Andvaranaut in Völsunga Saga and is forged by the dwarf Andvari.
Since smithcraft, with its forges and production of all sorts of fantastic items, can be seen as the ancestor of industrialism, later fantasy authors have often updated dwarves to be more technologically advanced than the other people of their world.
While every fantasy series tends to deal slightly differently with their fantasy races, there tend to be some common denominators.
- Dwarves are generally written as living underground.
- Dwarves are usually associated with mining, and with forging.
- In many fantasy stories, dwarves tend not be be traditional magic-users; in some stories, dwarves are naturally resistant to magic. Any magic they do use tends to be tied to their forging.
- (Dwarves are also usually short. Not sure that ties in, but it's hard not to note that.)
Living underground is difficult. Above ground, if you want to expand your house, you have to put up some new walls and extend the ceiling. Underground, you have to remove enough dirt/stone to form the rooms you want. You've got to leave enough rock to support the wieght of the earth above your home; or, provide additional support; otherwise, your new room could lead to your entire home/neighborhood/city being buried in a collapse.
Naturally, mining also involves the removal of large amounts of stone. However, it also entails the ability to determine what materials you may need are present (iron, gold, aluminum, precious stones, etc.), and how to extract them - again, without collapsing your underground structure.
If your magical talents don't lend themselves to this, you've got to develop things that do; tools (picks, shovels, wheelbarrows, mine carts, etc.; also anvils, tongs, and other forging tools), and science (physics, at a minimum to figure out how to safely remove all that stone, and to remove the materials you need intact; one imagines chemistry, in figuring out how to use some things that you may not use in forging ("Hey, look what happens when I take bat guano, sulfur, and some other stuff, mix it together, and set it on f..." BOOM)).