However, without considering the hidden corners where bodies are out of sight, let's talk about the corpses around Tang Ye. Excluding those killed by himself, the remaining zombies all share one trait, their heads are missing.
In the early Apocalypse, Tang Ye had taught Ah Fu to eat his own kind to stave off hunger. However, only the brain part of the body could provide Ah Fu and himself with the energy to remain active, because the brains contained the Evolution Crystal. Even if the brains of non-evolved zombies didn't have an Evolution Crystal, they were still its precursors. Consuming them could, more or less, replenish some energy.
At that time, when Ah Fu preyed on his own kind, he only ate the brains, leaving many headless zombie corpses behind, which bore a striking resemblance to the current situation. The sight before Tang Ye could only mean one thing: before his arrival, the zombies here indeed had been devouring each other, the strong preying on the weak.