De rebus in Oriente mirabilibus

De rebus in Oriente mirabilibus or Mirabilia Orientalia, also known as the Letter of Pharasmanes to Hadrian, is a short Latin text in the form of an epistolary periplus describing the natural and human marvels encountered by the writer on journeys through Mesopotamia, Arabia and Egypt. It is a pseudepigraphal work attributed to King Pharasmanes II of Iberia. It was written between the 2nd and 5th centuries AD.

De rebus may originally hve been written in Greek, but no Greek fragment survives. There are seven surviving Latin manuscripts, plus four known lost manuscripts. In addition, it was translated into Old English before the year 1000. Two illuminated manuscripts of the English text survive. By around 1300 an Old French translation appeared. It is known from a single manuscript.

Although De rebus originated as a letter describing journeys (with distances between places), its complex transmission has resulted in numerous variations across manuscripts. The original of some passages cannot be accurately reconstructed. The nature of the subject matter—the marvellous and monstrous—confounds efforts to understand the text logically.