History of Competitive DotA (The First Light of Dawn: The 6.2x Era)
The first league was Clan TDA (Team DotA Allstars) formed in April 2004. Its spread in popularity was helped in great part by the website DotA-Allstars.com founded on October 14th, 2004 by TDA member Pendragon.
IGS (International Gaming Syndicate) began hosting DotA competitions in 2004. The first season had 20 teams participating. The second season had 45 teams, so more and more people joined.
Happenings in the EU/NA scene
DotA's rapid popularization and balance improvements greatly increased DotA's competitiveness. Lots of teams began to emerge. Internationally renowned teams such as PluG (later known as coL or compLexity), Apex (later known as JMC or Jax Money Crew), Say Plz, Team Q, TeG (The Elder Gods) and BTo (Boomtown Odense, front-runner of JoY or Jukes on You and later, MYM or Meet Your Makers) were influential in competitions during this era. Some of these teams such as Apex had their beginnings in earlier leagues such as the IGS back in 2004-2005.
EU/NA competitions were mainly TDA and CAL, as well as Dota-League's Pick League. In the first season of Pick League taking place in November 2005, Team Q claimed victory, while BTo took first place in the next three seasons asserting their dominance.
Happenings in the Asian scene
Compared to these tournaments in EU/NA, DotA was still in an embryonic state in China. EU/NA competitions didn't have a big influence on the Chinese scene.
In China in the month of November 2005, some players famous on the U9 forum formed team GL under the leadership and organization of Xiaoxiongmao. Ever since they formed, GL has been one of China's strongest, mightiest and most low-profile teams. During the same period, Mage (not to be confused with later Russian team MaGe) and IFNT formed in succession.
The appearance of teams naturally led to contests. During the 6.2x era, there weren't many competitions. Everyone learned from each other by comparing their views on how to play the game. The records we have on matches back then doesn't amount too much. I've only noted down the influential competitions.
On February 7th 2006, a Taiwanese team was on the U9 forum challenging teams and met the recently-formed GL. Due to poor connections, the match wasn't very good. Nevertheless, the Taiwanese team used Keeper of the Light and Tinker's long-range nuke strategy which broadened the DotA worldview of GL, who had until then worked diligently on their AoE (area of effect) strategy. This also gave Chinese DotA players a taste of the fascination that exists in CW (clan wars). As the first CW match in China with some influence, it deserves mention in this history.
In March 2006, the first RDL DotA competition was hosted. Using 6.27 as the official version of the competition, the tournament originally planned to have 32 teams, but in the end only 23 teams participated. GL was too strong for the other teams and took the victory claiming the very first national Chinese title.
This tournament is something that can't be omitted from any Chinese DotA history. It could be argued that due to the experiment that was this tournament, more Chinese DotA experts switched from playing for amusement in pubs to having organized and competitive team games. This tournament also led to more people appreciating the competitive nature of DotA to break away from the preconception many people had of the game as a WC3 ladder map meant only for casual amusement.
This tournament spread the fame of first-generation Chinese teams such as GL, HUST, IFNT, Mage and EDU which declared the arrival of the strong teams. Following the popularization of replays, Chenlun, Huiyue, Xiaoxiongmao and mAroBoRo (Wanbaolu) and other players left a deep impression in people. They were the first generation Chinese DotA stars. They were also who DotA beginners tried to model themselves after.
During the 6.27 era, the mainstream strategy was AOE. For late-game, the 4-protect-1 strategy was also developed. The most famous strategy was the Divine Aegis (Divine Rapier, Aegis of the Immortal) Medusa. These strategies flourished through the 6.32 era until the 6.37 era.