This is a vintage Batak calendar, known as a Porhalaan, from Sumatra, Indonesia.
It is a traditional lunisolar calendar used by a shaman (datu) to determine auspicious dates for activities like weddings, planting crops, or traveling.
The calendar is typically made from materials such as wood and bamboo or bone.
The main body often features carved figures, in this case, two individuals riding figures that resemble horses.
The hanging strips contain inscribed calculations and astrological information. 35x9cm