Why were there fewer revolts in the Persian Empire than most of earlier empires?

The Persian Empire, under its different dynasties, was actually quite vulnerable to revolts and had in fact experienced multiple rebellions throughout its history. The Achaemenid Empire faced numerous uprisings from conquered territories including the Ionian Revolt, the Babylonian Revolt and the several revolts led by pretender kings (Pseudo-Smerdis, Vahyazdata and Phraortes). The Seleucid Empire also faced repeated rebellions and secessions from its territories: the Seleucid-Parthian Wars, Parthian separatism, Ptolemaic intervention, and finally the Maccabean revolt. However, it's true that the Persian Empire experienced relatively fewer revolts compared to some other large empires. Here are a few possible factors that may have contributed to this:

Effective Administration: The Persian Empire was known for its well-organized and centralized administrative system. Provinces were effectively governed through satrapies, each headed by a satrap appointed by the emperor. This structure helped maintain order and prevent widespread unrest.

Infrastructure Development: The Persians invested in building an extensive network of roads, canals, and other infrastructure. This facilitated efficient communication, transportation, and trade, fostering economic growth and reducing the risk of regional isolation or neglect that might lead to revolt.

Tolerance of Local Customs and Beliefs: The Persian rulers often respected local traditions, customs, and religions, rather than imposing their own. This conciliatory policy avoided cultural clashes that could spark conflicts and revolts.

Effective Military and Intelligence: The Persian Empire maintained a strong military capable of swiftly suppressing internal rebellions. Additionally, the empire's intelligence network helped monitor and mitigate potential threats.

Co-opting Local Elites: The Persians integrated powerful local elites into the imperial administration, giving them a stake in the empire's stability. This helped prevent potential internal rivalries and encouraged loyalty.

Royal Propaganda: The Persian emperors skillfully used propaganda to justify their rule and glorify their accomplishments. This helped generate loyalty and discourage revolts.

It's important to note that revolts did occur in the Persian Empire, but they were likely more limited in scale and frequency compared to some other empires due to the factors mentioned above.