The park of Phu Phra Bat holds more than its rocks, and what lies between them tells the story. Among the sandstone outcrops of this north-east Thai plateau, hundreds of stones have been set upright in the ground, flat slabs shaped like leaves, which are the sema that mark the boundary of a sacred space. This practice is typical of the Dvaravati period, between about the seventh and eleventh centuries, when Buddhism flourished in the region before the Khmer empire extended its power.
The sema are often carved with scenes from the Buddha's previous lives, the Jataka tales, in a style distinct from that of other regions. Around them the monks and lay people shaped caves into shrines, placed images of the Buddha under natural rock roofs, and carved steps to reach the best viewpoints. Later, the Lao and Khmer cultures left their own marks. The result is a landscape in which nature and devotion cannot be separated.
For a visitor, the walk is the point. Sandy paths wind between boulders, past caves like Tham Wua and Tham Khon, where fig roots grip the stone, and the forest is dry deciduous woodland of dipterocarps that turns green in the rainy season and dusty gold in the dry. Birdsong in the early morning is lovely, and so are the geckos in the caves. The ground can be slippery after rain, so wear shoes, and carry water, because the shade is patchy and the sun strong.
From a motorbike's point of view, the roads in this region are easy and quiet, with the odd stray dog and slow tractor. Fuel stations are frequent on the main highways, and Nam Som, Ban Phue and Udon Thani have a good choice of restaurants, with grilled fish, papaya salad and sticky rice as the staples. Weekdays are quiet, with Thai pilgrims arriving on holidays and festivals. A dawn visit gives you the best light and the cooler air.