The province on the northern tip of Sumatra island was ill-prepared,disaster struck in ruins, mired in poverty and with barely any functioning infrastructure after almost three decades of conflict.
Rebels in Aceh had spent years fighting against the central government for an independent state, a conflict that left at least 15,000 people dead, and a heavy military presence kept the area cut off from the outside world.
Almost 170,000 people were killed in the archipelago, the vast majority in Aceh, by far the biggest death toll in any single country. More than 220,000 people died in countries around the Indian Ocean, with Thailand and Sri Lanka also hard hit.
The disaster triggered a huge global relief and reconstruction effort that has been a success in Aceh. But just as importantly, it finally persuaded the rebels and Jakarta to strike a peace deal that has held to this day.
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Prospects for peace were already looking better before the tsunami, with a new government in Jakarta that seemed more determined to resolve the conflict and signs the rebels were growing weary, but the disaster provided the final push.
Under the deal between the Free Aceh Movement (GAM) and Jakarta, which was signed in Helsinki in August, 2005, the rebels agreed to give up their demands for independence in exchange for greater autonomy.
After a decade of post-tsunami reconstruction and nine years of peace, Aceh has been transformed. Provincial capital Banda Aceh is a pleasant, mid-size Indonesian city with few visible scars remaining from the disaster.