2 Chronicles 34:1

Josiah was eight years old when he began to reign; and he reigned thirty-one years in Jerusalem.

Jeremiah 1:2

to whom the word of Jehovah came in the days of Josiah the son of Amon, king of Judah, in the thirteenth year of his reign;

Zephaniah 1:1

The word of Jehovah that came unto Zephaniah the son of Cushi, the son of Gedaliah, the son of Amariah, the son of Hezekiah, in the days of Josiah the son of Amon, king of Judah.

1 Samuel 2:18

And Samuel ministered before Jehovah, a boy girded with a linen ephod.

1 Samuel 2:26

And the boy Samuel grew on, and was in favour both with Jehovah and also with men.

1 Kings 3:7-9

And now, Jehovah my God, thou hast made thy servant king instead of David my father; and I am but a little child: I know not to go out and to come in.

1 Kings 13:2

And he cried against the altar by the word of Jehovah, and said, O altar, altar! thus saith Jehovah: Behold, a child shall be born unto the house of David, Josiah by name; and upon thee shall he sacrifice the priests of the high places that burn incense upon thee, and men's bones shall be burned upon thee.

2 Kings 22:1-20

Josiah was eight years old when he began to reign; and he reigned thirty-one years in Jerusalem; and his mother's name was Jedidah, daughter of Adaiah of Bozcath.

1 Chronicles 3:14-15

Amon his son, Josiah his son.

2 Chronicles 24:1

Joash was seven years old when he began to reign; and he reigned forty years in Jerusalem; and his mother's name was Zibiah of Beer-sheba.

2 Chronicles 26:1

And all the people of Judah took Uzziah, who was sixteen years old, and made him king instead of his father Amaziah.

2 Chronicles 33:1

Manasseh was twelve years old when he began to reign; and he reigned fifty-five years in Jerusalem.

2 Chronicles 33:25

But the people of the land smote all them that had conspired against king Amon; and the people of the land made Josiah his son king in his stead.

Ecclesiastes 4:13

Better is a poor but wise youth than an old and foolish king, who knoweth no more how to be admonished.

Matthew 1:10-11

and Ezekias begat Manasses, and Manasses begat Amon, and Amon begat Josias,

Treasury of Scripture Knowledge

Summary

Josiah was eight years old when he began to reign, and he reigned in Jerusalem one and thirty years.

Bible References

Eight years

2 Chronicles 24:1
Joash was seven years old when he began to reign; and he reigned forty years in Jerusalem; and his mother's name was Zibiah of Beer-sheba.
2 Chronicles 26:1
And all the people of Judah took Uzziah, who was sixteen years old, and made him king instead of his father Amaziah.
2 Chronicles 33:1
Manasseh was twelve years old when he began to reign; and he reigned fifty-five years in Jerusalem.
1 Samuel 2:18
And Samuel ministered before Jehovah, a boy girded with a linen ephod.
1 Kings 3:7
And now, Jehovah my God, thou hast made thy servant king instead of David my father; and I am but a little child: I know not to go out and to come in.
Ecclesiastes 4:13
Better is a poor but wise youth than an old and foolish king, who knoweth no more how to be admonished.