In 2005, researchers at Manchester Metropolitan University Cheshire tested ski designs from as far back as 3200 BC to see what it’d take skiers to go from Point A to Point B:
The researchers tested a reproduction of the Salla ski, found in Finland and dated to 3200 BCE. These skis were flat, and skiers used just one pole to keep their balance, brake, and turn. Animal skins wrapped around the foot served as boots, a leather strap as binding. By 549 CE, the time at which the Mantta ski was used, skiers had added animal fur to the front half of the ski’s underside to get more grip during kicking. And instead of sinking into the snow, the skis could now float on it, thanks to an engraving that made the tip curve up.
The next skis, modeled after originals from 1300 CE, would be quite remarkable today. Skiers kicked on a short and glided on a long ski. Proper boots also entered with this design. At the end of the nineteenth century, cross-country skiing also became a leisure activity. Tar on the underside of the long ski reduced the amount of friction between ski and snow, and skiers now propelled themselves forward with two bamboo poles.
With the first Winter Olympic Games in Chamonix in 1924, cross-country skiing spread across the world. With processed snow and prepared tracks, skis became thinner, shorter, and lighter. Formenti and his colleagues tested the last wooden skis, from the 1970s, which were prepared with grip wax on the underside. In the 1980s, the use of the skating technique revolutionized cross-country skiing. Rather than kicking and gliding, skiers pushed forward like an ice skater. Both “skating” and “classical” skis are now made of very light carbon fiber and graphite.
Wikipedia has a great page on ski geometry if you want to look into this a bit more.