minetest.register_on_joinplayer(function(player)

        minp={x=500, y=-100, z=500}
        maxp={x=500, y=100, z=500}

        minetest.emerge_area(minp, maxp, placetreasure(minp, maxp, player))
end)

function placetreasure(minp, maxp, player)

    for cy=minp.y, maxp.y do
        pos={x=500, y=cy, z=500}
        node = minetest.get_node(pos)
        minetest.chat_send_all("Y=" .. cy .. "> " .. node.name)
    end
end