The sudden collapse of a mighty empire often happens exactly at the height of its power. After a single ruler conquers vast territories, his reign shatters and splits into smaller, weaker factions. Alexander the Great meets his end precisely at the peak of his strength and bravery [רש״י, מצודת דוד, ביאור שטיינזלץ]. His death comes at a young age, around thirty [אבן עזרא, מלבי״ם]. Rather than falling in battle, there is a view that he was poisoned by members of his own household [יוסף אבן יחיא]. Another perspective notes that his sudden end simply means he did not live to reach old age, dying in the middle of his life [יוסף אבן יחיא].
Following his passing, the massive empire is divided into four different directions: east, west, north, and south [רש״י, מצודת ציון]. These regions form four distinct kingdoms: Rome, Egypt, the Land of Israel, and Persia [מצודת דוד]. According to one perspective, the king himself actually initiates this division while still alive; sensing his strength failing, he hands control over to four officers from his family [יוסף אבן יחיא].
Crucially, the royal power does not pass to the king's own children [רש״י, מצודת דוד, ביאור שטיינזלץ]. The monarchy is completely uprooted from his immediate household [מצודת ציון, מלבי״ם, ביאור שטיינזלץ]. Even though a son is born to him after his death, this child is left without a crown because the empire has already been distributed to the officers and other family members [יוסף אבן יחיא].
The newly established kingdoms are significantly weaker. None of the four new rulers achieve the absolute power and control that Alexander once held [אבן עזרא, מלבי״ם]. Furthermore, the empire does not just stop at four divisions; it continues to crumble into the hands of other, minor rulers [מצודת דוד, מלבי״ם]. This extensive fragmentation sparks rebellions and conflicts. Rival kings rise against the four primary rulers, snatching territories from one another, much like the historical wars where the king of Greece conquered Egypt [אבן עזרא, יוסף אבן יחיא].