For some 2,500 years, residents of this mountainous village have used an astonishing language that only they understand.

But there are only six people left who can ‘speak’ it. Hidden deep in the south-east corner of the Greek island of Evia, above a twisting maze of ravines that tumbles toward the Aegean Sea, the tiny village of Antia clings to the slopes of Mount Ochi.

There are no hotels or restaurants within 40km, and the tiny place is so remote that it doesn’t exist on Google Maps. But as you travel here along a dizzying road from Karystos, through a mythical landscape of megalithic ‘dragon house’ stone tombs and giant Cyclopic boulders, you’ll hear an ancient siren song reverberating against the mountain walls. That’s because for thousands of years, the inhabitants of Antia have used a remarkable whistled language that resembles the sounds of birds to communicate across the distant valleys.