Iranian History Overview via Encyclopedia Iranica

There is a series of articles in Encyclopedia Iranica that present a broad overview of Iranian history, from prehistory through the end of the Iran-Iraq War in 1988. All of the articles were written by Ehsan Yarshater -- with help from any number of other scholars -- and they list a good deal of bibliography on the topics covered. The articles are freely available online. Links and a bit of info below...

1) Introduction to pre-Islamic Iran. Prehistory through the Sasanian collapse. [5th millennium BCE - mid 7th century CE]

2) Introduction to Islamic Iran. The Arab-Muslim conquest and its aftermath. Through early Abbasid period. [mid 7th century - ca. 800 CE]

3) The formation of local dynasties, or "Iranian Intermezzo". From Abbasid weakening to the Saljuq invasion. [early 9th century - mid 11th century CE]

4) From the Saljuqids through the Āq Qoyunlu. [mid 11th century - 1508 CE]

5) From the Safavids through the Zand consolidation. [early 16th century - late 18th century CE]

6) From the Qajars through the reign of Reza Shah Pahlavi. [late 18th century - late 1930s CE]

7) From the ouster of Reza Shah Pahlavi through the Iran-Iraq War. Concludes with extensive bibliography. [late 1930s - 1988 CE]

Iranica also put together a series of timelines of events related to Iranian history, "from the most ancient times to 2005." Incredibly useful: