The Co Loa citadel

The figures below come from a peer-reviewed report published in twenty ten by a Vietnamese and American team working on the site.¹

The inner enclosure is roughly rectangular, one thousand six hundred and fifty metres around, its wall some five metres high, six to twelve metres across the top and twenty to thirty metres across the base, with a number of bastions.

The middle and outer enclosures are both irregular in shape, measuring six and a half and eight kilometres around. In places the outer wall still stands three to four metres high and twelve to twenty metres thick; the middle wall runs about twenty metres wide and up to ten metres high.¹

Besides the three rings there are ditches running outside the ramparts, and raised mounds and towers. The archaeologists are careful about how far they will go here: those ditches may in ancient times have been moats connected to a reservoir inside the site — and that reservoir was fed by the Hoang river, which in turn joins the Red River.¹

In other words, this is not a wall. It is a system of earth, water and waterway, and it reaches all the way out to the largest river in the north.

The question everyone wants to ask is whether this citadel was An Duong Vuong's.

The honest answer is that archaeology cannot answer with a person's name. Earth does not record its owner. But it answers a different question, more concrete and no less important: when it was raised, and how many times.

In one section cut through the rampart, the team identified five construction phases belonging to three periods. The earliest phase dates to the fourth century BC or later; the next phases belong to a second period, the third century BC or later; and the last is a refurbishment of the fifteenth or sixteenth century AD.¹

The article's own summary puts it more briefly still: the main rampart of the middle circuit was built in the later centuries BC, before the coming of Han imperial China. Nor was this rampart the first defence.¹

Both halves are worth reading slowly. First, the dating overlaps the span the old histories give An Duong Vuong — which proves nothing about him, but rules nothing out either. The authors state their own limit plainly: the material evidence lends support to the possible existence of an Au Lac polity, but does not prove it unequivocally. They raise another possibility too: that Nam Viet, after taking the place around the early second century BC, may itself have added to the works.¹ Second, there were defences here before that rampart: the citadel did not rise once from one king's hand; it is a place people built up again and again across generations.

In two thousand four and two thousand five, the Vietnam Institute of Archaeology dug inside the inner enclosure. The earliest layer yielded firing kilns, bricks, stylised roof tiles, and stone moulds for casting bronze arrowheads.¹

A single charcoal sample from a trash pit beside a kiln used to make arrowheads returned a radiocarbon measurement of two thousand one hundred and ninety years before present, give or take thirty-five.¹

Outside the wall, five hundred metres from the south-east corner of the inner circuit, excavators recovered the Co Loa bronze drum: seventy-two kilograms, the largest recovered from the region, holding some two hundred bronze objects — among them ninety-six ploughshares, six hoes, a chisel, and an assortment of axes, spearheads, daggers and arrowheads.¹

And at Cau Vuc, just outside the southern entrance, a hoard of about ten thousand tanged bronze projectile points.¹

Set those four things side by side — moulds for arrowheads inside the walls, a hoard of arrowheads outside the south gate, a seventy-two kilogram drum packed with nearly a hundred ploughshares, and three ringed ramparts with ditches running out to the river — and what appears is a place farming, casting bronze and preparing for war at once, on a scale no village could manage.

The archaeologists do not discuss the legend of the magic crossbow. But the boundary should be drawn plainly here: the moulds and the arrowhead hoard are objects; "one shot kills three hundred men" is a line in a book. That the two suit each other is interesting, but suiting is not proving — bronze arrowheads are found across the whole Dongson culture, not only here.

Among the measurements and the dates there is one small detail worth its own place.

In nineteen seventy, at a collapsed stretch of the outer rampart, Vietnamese investigators examined the break and found Dongson culture potsherds lying in a layer beneath the body of the wall.¹

That is to say: before there was a rampart, people were living there. The wall was raised on top of the traces of their daily life.

A story needs a king to arrive from somewhere and raise everything. The layers of soil tell it differently: people were here first, and the wall came after.