According to Vedic literature, there are mentions of pāpa-yoni. Yoni means species. Pāpa-yoni. Just like it is mentioned here, striyaḥ śūdrāḥ, striyo vaiśyās tathā śūdrās te 'pi yānti parāṁ gatim. Even the striyaḥ, even women, they are also classified amongst the pāpa-yoni. Pāpa-yoni means those who have got little facility for advancing themselves in spiritual life. So it is particularly mentioned here, striyaḥ, the woman class; śūdra—śūdra means the laborer class—and the vaiśya, mercantile class. Or less than that.
Because in India, according to the caste system, or varṇāśrama-dharma, the brahmin and kṣatriyas are considered to be the highest in the society, and the vaiśya, a little less than them, and śūdra, they are not taken into account. In the similarly, woman class, they are taken as śūdra. Śūdra. Just like the thread ceremony is given to the brāhmaṇa, kṣatriya, vaiśya, but there is no thread ceremony for the woman class. Although the woman is born in the brahmin family, she has no that reformation. Because striyaḥ, woman class, are taken less intelligent, they should be given protection, but they cannot be elevated.
But here in the Bhagavad-gītā, He surpasses all these formalities. Lord Kṛṣṇa surpasses all these formalities. He is giving facility to everyone, never mind what he is. In the social structure, you may consider that woman is less intelligent or śūdra . . . or less purified, but in spiritual consciousness there is no such bar.