In other words, it's time for both sides to create teams of three, one from each kingdom, & see which one stands tall over a not-so-unified China!
In Japan Romance is a highly beloved tale, so the idea of adapting it into anime back in the 80s, which (to my knowledge) had not been done yet at that point, was likely taken as a big deal. Therefore, it's not all that much of a surprise that when the first (still existing) anime adaptation of Romance debuted in Japan, it was given some special treatment. Namely, on March 20, 1985 Nippon TV aired the made-for-TV anime movie (also sometimes referred to as a TV special) Sangokushi on its Wednesday Road Show program. There is apparently a TV anime special from 1982 also called Sangokushi, produced by Studio Sangosho & Tezuka Kikaku (no relation to Tezuka Productions?), but it looks to have become lost media & information about it is extremely scarce. Anyway, WRS ran from 1972 to 1985 & was the Japanese equivalent to something like NBC's Saturday Night at the Movies & its many imitators (before the home video market this was how people could watch hit movies at home), and would be replaced with Friday Road Show on October 4, 1985, which NTV still airs to this day. This movie would get re-aired in March of 1986 on FRS in order to get viewers ready for its sequel, Sangokushi II: Amakakeru Otoko-tachi/Soaring Manly Heroes, which first aired on FRS on August 22, 1986. Produced by NTV for 150 million yen (though this amount might only be for the first film?), these movies were animated by Shin-Ei Animation, the studio best known for Doraemon & (later) Crayon Shin-chan, both of which are still in production to this day. These movies also credit themselves as being adaptations of Mitsuteru Yokoyama's Sangokushi manga that was still running at the time, to the point that Hikari Production is on the copyright for them, but aside from telling (portions of) the same source story they really aren't, especially visually. These two movies would find themselves fans, such as Masami Tsuda, who'd later go on to be the creator of the manga His & Her Circumstances. However, possibly unbeknownst to Shin-Ei & NTV at the time, there was actually another anime adaptation of Romance in the works while these two movies debuted on TV in Japan, though this wouldn't finally appear until years later.
In the early 80s the production company Shinano Kikaku, formerly (& literally) Soka Gakkai Public Relations Bureau, started production on its own anime adaptation of Romance, hiring Toei Animation to do the animation itself. After 10 years & a budget of 1.5 billion yen, ten times the cost of NTV & Shin-Ei's movies, Shinano Kikaku would finally release Sangokushi Part 1: Eiyuu-tachi no Yoake/Dawn of the Heroes in theaters on January 25, 1992. Yes, much like NTV's movies this was also a multi-part production, three parts this time instead of two, but unlike those movies this trilogy of films were released in theaters on a yearly basis, with the second film, Part 2: Choukou Moeyu!/The Yangtze Burns!, debuting on March 20, 1993, & the third film, Part 3: Harukanaru Daichi/Distant Lands, on April 9, 1994. The first of these films would actually see an official English release as well, as Streamline Pictures would license, dub, & release Dawn of the Heroes in the 90s under the title Great Conquest: The Romance of the Three Kingdoms, even hiring the late Pat Morita to act as the narrator for the dub; Streamline's dub, though, did also cut down the film to 120 minutes, from its original 140 minutes. In 2020 Discotek Media, during its now defunct working relationship with Enoki Films (which handles international licensing for these films, on behalf of Shinano Kikaku), would re-release Great Conquest on double-disc DVD, with the first disc including Streamline's cut down dub & the second including the original uncut Japanese version with English subtitles for the first time, though the other two films would never see official release in English; this would also be the final DVD release Discotek would ever do, as they've only released on Blu-Ray since.
So, with two different anime movie series calling themselves "Sangokushi", which one comes out without rival: NTV or Shinano?