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Ask MOA: What Are These Engraved Bones?

Ask MOA: What Is It? is your opportunity to ask MOA Curators and Collections staff about an artwork or other mystery object at home that you’ve always wondered about. We select certain inquiries and objects to feature online.

This featured Ask MOA case is about engraved bones found in the communal items place in the inquirer’s building.

Question from inquirer:

“I found these pieces in my building’s communal items place that someone had gotten rid of. I snatched them up and was drawn to them. But I am unsure of their origins. They appear to document something and are carved on bones? Just wondering if this is something that should be donating to the museum? Or maybe you can help me learn more about it?”

Answer from Fuyubi Nakamura:

I think these are calendar bones from Indonesia known as porhalaan. More specifically, they are made by the Batak people of North Sumatra. The Batak calendar is used for divination, rather than telling time and provides a unique insight into an Indigenous culture of Southeast Asia. The porhalaan consists of twelve or thirteen column grids. Knowledge of the porhalaan was limited to the traditional knowledge and ritual keepers known as datu. The porhalaan was also engraved on bamboo.

The name, porhalaan means “the scorpion thing,” that drives from hala or the scorpion, an important being in the Batak cosmology. A large scorpion was considered to reside in the underground, and its movement affected the affairs in the middle world where humans live. The placement of the scorpions on the grids varies, but there are some general patterns. There is always at least one scorpion in each column on the grids as you see in the image.


Kimball, Linda Amy, “The Batak Porhalaan Traditional Calendar of Sumatra.” In Archaeoastronomy; 1989, Volume 11, pp.28 –56.

Batak Calendar on