The Irdinmanhan age is a period of geologic time (48.6—37.2 Ma) within the Middle Eocene epoch of the Paleogene

Paleogene

The Paleogene is a geologic period and system that began 65.5 ± 0.3 and ended 23.03 ± 0.05 million years ago and comprises the first part of the Cenozoic Era...

 used more specifically with Asian Land Mammal Ages

Asian land mammal ages

The Asian Land Mammal Ages establishes a geologic timescale for prehistoric Asian fauna beginning 58.7 Mya during the Paleogene and continuing through to the Middle Pleistocene...

. It follows the Arshantan

Arshantan

The Arshantan age is a period of geologic time within the Early Eocene epoch of the Paleogene used more specifically with Asian Land Mammal Ages. It follows the Bumbanian age and precedes the Irdinmanhan age....

 and precedes the Sharamurunian

Sharamurunian

The Sharamurunian age is a period of geologic time within the Middle Eocene epoch of the Paleogene used more specifically with Asian Land Mammal Ages...

 age.

The Irdinmanhan's lower boundary is the approximate base of the Lutetian

Lutetian

The Lutetian is, in the geologic timescale, a stage or age in the Eocene. It spans the time between and . The Lutetian is preceded by the Ypresian and is followed by the Bartonian. Together with the Bartonian it is sometimes referred to as the Middle Eocene subepoch...

 age and upper base of the Priabonian

Priabonian

The Priabonian is, in the ICS's geologic timescale, the latest age or the upper stage of the Eocene epoch or series. It spans the time between and...

 age. The Irdinmanhan age is named after the Irdinmanha fossil formations in Mongolia

Mongolia

Mongolia is a landlocked country in East and Central Asia. It is bordered by Russia to the north and China to the south, east and west. Although Mongolia does not share a border with Kazakhstan, its western-most point is only from Kazakhstan's eastern tip. Ulan Bator, the capital and largest...

.