The feeling of Bhakti or devotion can be traced back to the Rigveda. It is the very first hymn of the Rigveda, which gives expression to a feeling of intimacy with the highest god. In the Katha Upanisad it is said that the divine help, which is the reward to Bhakti, is necessary before one can be saved. The Sveta-svatara Upanishad speaks of the highest devotion to God. Panini refers to the object of devotion in the Astadhyayi. The earliest god connected with bhakti is Vishnu-Krishna. In the Bhagavadgita there is emphasis on love and devotion to God. The attitude of love to the Supreme God continued to be recommended in the Bhagavata Purana.

The downfall of Hindu political power in northern India was remarkable change to Hinduism. For over one hundred years Hinduism lay prostrate before the invader. It was also deprived of political, social and intellectual leadership. Slowly Hinduism recovered from the conquest and everywhere in Hindustan an intellectual and moral revival of Hinduism becomes visible. Prior to the Muslim invasion Sankara had successfully refashioned Hindu doctrines. Later the great Acharyas Ramanuja, Madhva and others further strengthened these doctrines by their teachings.

The Nature of the Bhakti Movement
Generally speaking the religious movement of this period that lies between 1300-1550 A.D. were non-ritualistic and mainly based on Bhakti. It emphasized a religion or faith, which was essentially Hindu but reflected the vigorous monotheism of Islam. All Bhakti cults are essentially monotheistic. It is immaterial whether he is called Siva, Krishna or Devi. They all symbolize the One and the Eternal. It is the religion, philosophy and social thinking that were created during this revival, which enabled Hinduism to reassert itself in the following period. In the religious life of India the glory of the period is most resplendent. Ramanand, Kabir, Mira, and Vallabhacharya in the north, Chaitanya in Bengal, Madhva, Vedanta Desika and numerous others in the south give to the religious life of the period a vitality that Hinduism never seems to have enjoyed before.

Characteristics of Bhakti Movement
One chief characteristic of the Bhakti movement can be mentioned as belief in one God. A devotee could worship God by love and devotion. The second characteristic of the Bhakti movement was that there was no need to worship idols or to perform elaborate rituals for seeking his grace. The third feature on which the Bhakti saints laid stress was the equality of all castes. There was no distinction of high or low as far as the devotion to God was concerned. The fourth feature was the emphasis, which these saints laid on Hindu-Muslim unity. According to these saints all men irrespective of their religion are equal in the eyes of God.

The saints preached in the language of the common people. They did not use Sanskrit, which was the language of the cultured few. These saints laid stress on purity of heart and practice of virtues like truth, honesty, kindness, and charity. According to these saints only virtuous man could realize God. These saints considered God as omnipresent and omnipotent. Even a householder could realize God by love and devotion. Some saints regarded God as formless or Nirguna while others consider him as having different forms or Saguna.

The basic principles of the Bhakti movement namely love and devotion to one personal god and the unity of God were mainly Hindu. But as a result of contact with Islam more emphasis was laid on these principles than performance of outward rituals such as Yajiias, fasts, going to sacred places, bathing in the Ganges or worship of images.

The Movement had two main objects in view. One was to reform Hindu religion to enable it withstand the onslaught of Islamic propaganda. And the second was to bring about a compromise between Hinduism and Islam.

Factors that helped the development of the Bhakti movement
There were a number of factors, which contributed to the rise, and growth of the Bhakti movement during the medieval period. The first important factor was the destruction of Hindu temples by the invaders. They destroyed idols of Hindu gods and goddesses. The Hindus lost faith in the dependability of their religious rites and, therefore, chose the path of love and devotion.

The second factor can be presumed as the persecution of Hindus by the Muslim rulers, who tried to convert them to Islam and imposed jaziya if they were not prepared to become followers of Islam.

The third factor was the ill treatment of the lower classes in Hindu society by the persons of upper castes. The people of the lower castes had to suffer injustice and cruelties. So the teachings of the Bhakti saints who preached equality of castes as far as the devotion to God was concerned appealed to the people of lower castes.

The fourth factor was the elaborate rituals that the common man disliked. The Bhakti saints preached the path of devotion and discarded all rituals hence it appealed to the common man.

The fifth factor was the enthusiasm and the inspiration of the Bhakti saints. They tried to remove the evils of Hindu society and gave it a new vigor and vitality.

The sixth factor was the inner vitality of Hindu religion that resulted in an intellectual and moral revival of Hinduism. This Hinduism affected every aspect of thought and generated new moral forces, which helped to revitalize Hindu life, and gave it the dynamism. In the sphere of religion and normal thinking in law, in literature and even in political ideals, a new life came into being in India by the middle of the 16th century which KM. Panikkar termed the first Indian Renaissance.

Indian Bhakti Preachers
There are some personalities that are known as the saints of Bhakti movement and they are widely respectable.

Ramanuja
The first great exponent of Bhakti was Ramanuja. He lived in the eleventh century. He asked his followers to worship Vishnu. He did not believe in Sankara`s Advaita doctrine according to which the universal soul and the individual souls are one. According to Ramanuja the individual souls exhale from him but are not essentially one with the Supreme Reality. He, therefore, preached that the individual souls should seek His grace by love and devotion to him. His teachings appealed to large numbers of man in South India.

Ramananda
Ramananda flourished in North India in the fourteenth century. He entirely discarded the theory of caste system by birth. He preached the worship of Rama and Sita. Persons of all castes became his disciples. Among his chief disciples there was a barber, a chamar and a weaver. He preached in Hindi, which was the language of the common man in northern India. His followers are worshippers of Rama whom they regard an incarnation of Vishnu.

Kabir
The life of Kabir is totally unknown to the humankind. A true proponent of the Bhakti Movement Kabir was a holy soul who further preached about the unity of Hindu and Muslim.

Guru Nanaka
Nanaka was born in 1469 in the village to Talwandi. Presently the place is known as Nankana in the Sheikhupura district of West Punjab. His parents belonged to Khatri caste. His father Kalu was the Patwari of the village. Nanaka was educated in the village school. From his boyhood he showed a religious bent of mind and paid no attention to his studies.

Vallabhacharya
Vallabhacharya was a Tailang Brahmana. He preached the worship of Vishnu in the form of Krishna. He was born in 1479 in the Telugu country. He visited Mathura, Vrindaban and many other sacred places and finally settled at Benaras.

Chaitanya:
Chaitanya was the greatest saint who preached the worship of Krishna and Radha. Chaitanya was born at Navadwipa in 1486. His father Jagannatha Misra was a religious and scholarly man and his mother Sachi was also a pious and religious minded lady. Chaitanya as a boy was an exceptionally brilliant student.