There are some secondary sources outside the bible that mention him or followers of him... I coped them from a source as it has what they mentioned and it was easier than summing it up..

-- FLAVIUS JOSEPHUS

Josephus was a Jewish historian who was born around AD 38. He served Roman commander Vespasian in Jerusalem until the city's destruction in AD 70. Josephus personally believed Vespasian to be Israel's promised Messiah. When Vespasian later became emperor of Rome, Josephus served under him as court historian. 2 In AD 93, Josephus finished his work Antiquities of the Jews in which at least three passages specifically confirm portions of Scripture:

But to some of the Jews the destruction of Herod's army seemed to be divine vengeance, and certainly a just vengeance, for his treatment of John, surnamed the Baptist. For Herod had put him to death, though he was a good man and had exhorted the Jews to lead righteous lives, to practice justice towards their fellows and piety towards God, and so doing to join in baptism. 3

...convened the judges of the Sanhedrin and brought before them a man named James, the brother of Jesus who was called the Christ, and certain others. He accused them of having transgressed the law and delivered them up to be stoned. 4

At this time there was a wise man who was called Jesus. And his conduct was good, and [he] was known to be virtuous. And many people from among the Jews and the other nations became his disciples. Pilate condemned him to be crucified and to die. And those who had become his disciples did not abandon his discipleship. They reported that he had appeared to them three days after his crucifixion and that he was alive;...

-- PLINIUS SECUNDUS (Pliny the Younger)

Pliny was the governor of Bithynia in Asia Minor. Much of his correspondence has survived including a particular letter written circa AD 112 to the Roman emperor Trajan. This letter does not reference Christ directly, but it does establish several beliefs and practices of early Christians. This includes their loyalty to Christ even when it cost them their lives. Pliny's letter states:

In the meantime, the method I have observed towards those who have been denounced to me as Christians is this: I interrogated them whether they were in fact Christians; if they confessed it, I repeated the question twice, adding the threat of capital punishment; if they still persevered, I ordered them to be executed.

...They affirmed, however, that the whole of their guilt, or their error, was that they were in the habit of meeting on a certain fixed day before it was light, when they sang in alternate verses a hymn to Christ, as to a god, and bound themselves by a solemn oath, not to perform any wicked deed, never to commit any fraud, theft or adultery, never to falsify their word, nor deny a trust when they should be called upon to make it good; after which it was their custom to separate, and then reassemble to partake of food - but food of an ordinary and innocent kind.

-- CORNELIUS TACITUS

Tacitus was a senator under Emperor Vespasian and later became governor of Asia. Around AD 116 in his work entitled Annals, he wrote of Emperor Nero and a fire which had swept Rome in AD 64:

Consequently, to get rid of the report, Nero fastened the guilt and inflicted the most exquisite tortures on a class hated for their abominations, called Christians by the populace. Christus, from whom the name had its origin, suffered the extreme penalty during the reign of Tiberius at the hands of one of our procurators, Pontius Pilate, and a most mischievous superstition thus checked for the moment, again broke out not only in Judea, the first source of the evil, but even in Rome...

-- GAIUS SUETONIUS TRANQUILLAS

Suetonius was a chief secretary to Emperor Hadrian writing around AD 120 in his work Life of Claudius:

Because the Jews at Rome caused continuous disturbances at the instigation of Chrestus, he expelled them from the city.

-- LUCIAN

Lucian, the Greek satirist, wrote this rather scathing attack in The Death of Peregrine circa AD 170:

The Christians, you know, worship a man to this day - the distinguished personage who introduced their novel rites, and was crucified on that account... You see, these misguided creatures start with the general conviction that they are immortal for all time, which explains the contempt of death and voluntary self-devotion which are so common among them; and then it was impressed upon them by their original lawgiver that they are all brothers, from the moment that they are converted, and deny the gods of Greece, and worship the crucified sage, and live after his laws.

-- THE TALMUD

The Talmud is essentially the collection of Jewish oral traditions that were put into writing with additional commentary between the years of AD 70 and 200. From the Babylonian Talmud, Sanhedrin 43a includes:

On the eve of Passover they hanged Yeshu. And an announcer went out, in front of him, for forty days (saying): 'He is going to be stoned because he practiced sorcery and enticed and led Israel astray. Anyone who knows anything in his favor, let him come and plead in his behalf.' But, not having found anything in his favor, they hanged him on the eve of the Passover.

The facts in this passage are somewhat difficult to assimilate. Although Yeshu is referring to Jesus, the announcement that he was to be stoned (a lethal punishment) is followed by the statement that he was hanged (crucified). One possible explanation is that the Jewish leadership's call for his stoning preceded his eventual arrest by at least those forty days. This would be consistent with Scripture's accounts of his numerous near-stonings (John 10:31-33, 11:8).

Jesus' death by crucifixion may have then just been a matter of Roman involvement in the affair. Perhaps it is more likely that his sudden crucifixion (which immediately followed his arrest and dubious midnight trial) was gladly allowed by the Jewish leaders to pre-empt the normal forty day holding period for a condemned man. The leaders may have feared that, during this time, Jesus' followers might have been able to organize his release or stir up an outcry against them.