dt_info = []
for i in range(0, terrorism_data.shape[0]):
    dt_info.append(str(terrorism_data.year.values[i]) + str(terrorism_data.month.values[i]) + str(terrorism_data.day.values[i]))
terrorism_data["date"] = pd.to_datetime(dt_info, format='%Y%m%d', errors='coerce')