Spanish era

[1] Isidore of Seville in his Etymologiae (early 7th century) included an explanation of the meaning of Latin aera, plural of aes (bronze, brass, copper).

"An era", writes Isidore, "according to the sequence of the years was set up by Caesar Augustus when he first levied a general tax and mapped the Roman world [i.e., in 38 BC].

[5][6] Alternatively, Giorgio Levi Della Vida interprets it as "Bronze Era", with ṣufr corresponding to Latin aera, i.e.

This derivation is supported by a legend recorded in the 12th-century Chronica Gothorum Pseudoisidoriana and interpolated in the Arabic translation of Orosius' Historiae adversus paganos.

According to this legend, Augustus in 38 BC taxed the whole empire in bronze or copper coin and melted it down to make plates with which he covered the banks of the Tiber.