The ‘Leiden Plate’ or ‘Leiden Plaque’ owes its name to the circumstance that the first publications dealing with it appeared in the English language. Actually, it is a pendant made of Middle-American jade which was found by chance in 1864 by a Dutch engineer who was in charge of the digging of a canal in the vicinity of Puerto Barrios in Guatemala, where he came across bronze and jadeite objects.
The Leiden Plate owes its importance to the fact that one of the oldest known recorded dates of the Maya calendar is engraved on it and has been preserved intact. The text reads as follows: After the period composed of 8 baktuns, 14 katuns,3 tuns, 1 uinal and 12 kins, on the day 1 Eb, when the fifth Lord of the Night ruled and the month Yaxkin commenced, Balam-Ahau-Chan, ruler of [probably] Tikal, was installed. This refers to the date on which Balam-Ahau-Chan ascended the throne, in our calendar corresponding with Friday, the 17th of September, AD 320.
The other side shows Balam-Ahau-Chan with such regalia as the double-headed serpent staff, which he holds horizontally in his arms. This headdress is topped by the face of the Jester god, the symbol of royal power. The king stands on a vanquished man whose hands are tied and whose head is turned away. Because the Leiden Plate was found together with small bells made of bronze – which did not come into use until the end of the classic period – we know that this pendant was looted from a grave by Mayas around that time (AD 800-900) and was used and reburied. The possession of a pendant of this kind enhanced the value of the kingship and of the king himself, as Balam-Ahau-Chan showed by hanging three “Leiden plates” from the right and left sides of his girdle.
Source: RMV inv.nr. 1403-1193