A colossal dragon composed of Human Warriors tore open the Tians' defenses with the most direct self-sacrificial method.
The Tians are like dragons in human form, and only upon reaching the battlefield will one understand the magnitude of the scene.
From birth, the Tians possess strength comparable to the Human race's heavyweights, and reaching adulthood as a semi-king or king is merely a matter of time; thus, their small numbers are only relative.
They pride themselves on being higher life forms because of their absolute power. To face such an enemy, humans can only fight life for life, trading the lives of billions for a single Tians' king's life - how terrifying!
Through eternal ages, during two human conquests of the Heavenly Path, the Tians, although numerous, adhered to the rule that the higher the life level, the harder it is to have offspring.
It's somewhat pitiful to say, but the population became humanity's only advantage against the Tians!
"Kill! Kill! Kill!"