A ∼2500 year record of hydrologic change from southern Iran is inferred from the mineralogy and stable isotopic composition of bulk and biogenic carbonates archived in Lake Hirom (27º 57’N, 53º52’E). This change is related to regional variations in moisture and to the larger Indian Summer Monsoon circulation (ISM). During the early Holocene, increased summer insolation from ~10,000 to 8,000 yr BP contributed to the intensification of the ISM. This intensification may have increased summer precipitation north of the modern ISM limit. Evidence of wetter lake conditions in Lake Hirom occur from 8,800 to 7,800 yr BP. Drier conditions occur and persist from 7,800 to 6,300 yr BP, until lacustrine marl changes to peat, indicating maximum aridity. The timing of the drying trend in the mid-Holocene of Lake Hirom correlates with cave and lake records in the Arabian Peninsula, and lake records in northern Iran, indicating a regional drying event.