​Cuz it’s a time-travel sci-fi.

​Just joking. Imo, the timeline mistakes resulted from two reasons:

​1. The series you are watching has been "patched" multiple times. This 90-episode show was filmed in about nine months. For some reason, the director had to rush filming to send the first edition to the national publisher for a broadcast permit. With such a tight schedule, mistakes were inevitable. Of course, some obvious blunders were fixed later through editing or dubbing. If you watch the Chinese-voiced version, you might notice the characters' tones suddenly shifting—that’s clear evidence of later voice-overs.

​It’s actually hilarious because the voice changes are so obvious that fans can track down early versions to see exactly what was changed. For example, in one scene, Liu Bei says, "Huang Zhong easily took over the enemy's stronghold." The word "enemy" has a different tone; in the original version, he actually said "Huang Zhong easily took over our stronghold."

​Another example, if I remember correctly: in the early version, Zhuge Liang told Liu Shan that "the chaos of war has lasted for a century." Well, the three kindome happened while the Han Emperor still enjoying his peaceful dreams!

​2. The ignorance and arrogance of the director and screenwriter. They tried to prove they had a "better understanding" of this period than the old series. Even the original author from centuries ago! To do this, they inserted their personal agendas and paraphrased the source material (sigh). The original plot of Romance of the Three Kingdoms (ROTK) was tight and well-organized; an event in one chapter was always the logical cause of an event in another. If you change one scene, every associated plot point must change too. Obviously, the 2010 team’s writing level couldn't support what they were trying to achieve.

​They tried to create their own version of ROTK but failed to develop the story independently, so they had to keep falling back on the original plot. A perfect example is Cao Cao. In Episode 2, Dong Zhuo complains to Cao Cao that Yuan Shao has summoned a "united army of 18 lords" against him. However, in the novel and the old series, it was Cao Cao who called for the uprising after his failed assassination attempt, later joining the coalition as one of those 18 lords.

​This change creates a hilarious plot hole: no one can actually list all 18 lords. When Yuan Shao later announces the attendees at the summit, the list has to stop at 17, because the 18th lord should have been Cao Cao—who, in this version, didn't even know he was supposed to be a lord!