The correct option is 2 - 1 - 3 - 4.
Explanation
The question requires establishing the chronological sequence of key political events in ancient India, specifically spanning the transition from the Nanda period to the rise, zenith, and decline of the Mauryan Empire.
- 1. Accession of Chandragupta Maurya: Chandragupta Maurya ascended the throne around 321 BCE. With the help of Chanakya (Kautilya), he overthrew the Nanda dynasty and established the Mauryan Empire. This event occurred shortly after the power vacuum created by Alexander's retreat.
- 2. Invasion of Alexander of Macedon: Alexander invaded the northwestern part of the Indian subcontinent in 327-326 BCE. His campaign destabilized the local republics and monarchies, which indirectly facilitated Chandragupta's subsequent consolidation of power. Thus, this event precedes the Mauryan accession.
- 3. Reign of Asoka: Ashoka, the grandson of Chandragupta Maurya, ruled from approximately 268 BCE to 232 BCE. His reign represents the peak of the Mauryan Empire, occurring well after its foundation.
- 4. End of the Mauryan Empire: The Mauryan Empire formally ended in 185 BCE when the last Mauryan ruler, Brihadratha, was assassinated by his commander-in-chief, Pushyamitra Shunga, who then established the Shunga dynasty.
Chronological Order: Invasion of Alexander (326 BCE) → Accession of Chandragupta (321 BCE) → Reign of Asoka (268 BCE) → End of the Mauryan Empire (185 BCE).
Key Takeaway: Alexander's invasion (late 4th century BCE) acted as a precursor to the political unification of India under Chandragupta Maurya, while Ashoka's reign and the empire's eventual collapse occurred in the 3rd and 2nd centuries BCE, respectively.