def get_device_family_chipset(vendor_id, device_id, device_map):
    """Get the family and chipset strings given the vendor and device ids.

    Args:
        vendor_id: a string representing the vendor id (e.g. '0xabcd').
        device_id: a string representing the device id (e.g. '0xbcde').

    Returns:
        A string in the format "Device Family Name-Chipset Name".

    """
    if vendor_id not in device_map:
        return "Unknown"

    if device_id not in device_map[vendor_id]:
        return "Unknown"

    return "-".join(device_map[vendor_id][device_id])